EXPERIMENTAL  PHYSIOLOGY 
AND  ANATOMY 


WALTEU  HOLLl:-:  Vi>DY 


GIFT  OF 


BIOLOGY 

J-IBRARY 

G 


EXPERIMENTAL  PHYSIOLOGY 
AND  ANATOMY 


FOR 


HIGH  SCHOOLS 


BY 

WALTER  HOLLIS  EDDY 

Chairman    of  the  Department   of  Biology   in 
The  High  School   of  Commerce 
New  York  City 


•  *•    •       •»„„"***.•**•     • 

'         »'  *   _L_1     •*•••••*    • 


NEW  YORK    • :  •    CINCINNATI    •  I  •    CHICAGO 

AMERICAN    BOOK    COMPANY 


f  y 


OIOLOGY 

LIBRARY 

G 


COPYRIGHT,  1906,  BY 
WALTER  HOLLIS  EDDY 


Eddy's  Experimental  Physiology 
W.  P.  2 


PEEFACE 

THOUGH  the  importance  of  Physiology  in  secondary  schools 
is  everywhere  recognized,  little  attempt  has  been  made  to 
place  the  subject  on  an  experimental  basis.  This  book  has 
been  prepared  in  an  effort  to  call  attention  to  the  great  field 
which  this  subject  presents  for  laboratory  study. 

The  starred  topics  in  the  following  table  of  contents  con- 
stitute a  brief  course  covering  that  which  is  essential;  and 
the  optional  exercises  make  it  possible  to  extend  the  work  at 
the  discretion  of  the  teacher.1  The  ingenuity  of  the  teacher 
will  readily  suggest  substitutes  for  the  material  suggested  when 
the  laboratory  facilities  of  the  school  are  inadequate. 

Some  of  the  exercises  may  be  made  demonstrations,  and 
time  in  school  may  also  be  saved  by  assigning  some  of  the 
simpler  exercises  as  part  of  the  home  work  of  the  pupil. 

I  wish  to  acknowledge  the  many  helpful  suggestions  given 
me  by  my  colleagues  of  the  High  School  of  Commerce  and 
by  members  of  the  Columbia  University  faculty.  I  have 
also  found  many  useful  suggestions  in  the  works  of  Messrs. 
Foster  and  Langley,  J.  E.  Peabody,  M.  L.  Macy,  H.  Newell 
Martin,  Hammarsten,  Verworn,  Wilson,  and  Schafer. 

I  wish  also  to  express  my  great  indebtedness  to  Dr.  E.  A. 
Darling  of  Harvard  College  and  to  Mr.  Frank  O.  Payne  of 
the  High  School  of  Commerce  for  their  critical  review  of  the 
manuscript  and  for  the  aid  they  have  given  me  in  its  prepara- 
tion; and  to  my  wife  for  great  assistance  in  the  many  details 
of  grammatical  arrangement  and  mechanical  labor  involved 
in  the  work.  W  H  E 

THE  HIGH  SCHOOL  OF  COMMERCE, 
NEW  YORK  CITY. 

1  The  book  in  its  starred  topics  meets  the  requirements  of  the  New  York 
State  Syllabus,  and  as  a  whole  has  been  accepted  by  the  Harvard  College 
authorities  as  meeting  the  entrance  requirements  of  that  institution. 

3 

255376 


METHOD    OF   EXPERIMENT 

IT  has  been  the  purpose  of  the  author  so  to  state  each 
of  the  following  exercises  as  to  admit  of  its  performance 
by  the  pupil  with  a  minimum  amount  of  direction  from 
the  teacher.  Most  of  the  exercises  should  be  thus  per- 
formed by  each  pupil  individually,  or  by  two  pupils  to- 
gether; but  of  course  the  teacher  may  select  as  many  as 
desired  for  performance  as  demonstrations  before  the  class. 

It  is  essential  that  each  pupil  make  a  suitable  record  of 
all  exercises  performed,  in  a  carefully  prepared  notebook. 
It  is  recommended  that  a  separate-leaf  notebook  be  used 
for  this  purpose,  as  this  makes  possible  the  inspection  of 
one  set  of  exercises  without  handling  the  entire  books, 
and  permits  the  rewriting  of  unsatisfactory  work  without 
disturbing  the  arrangement  of  the  book. 

It  is  generally  agreed,  too,  that  the  book  should  consist 
of  original  reports  made  at  the  time  of  experiment,  and  not 
of  matter  copied  from  original  rough  drafts. 

Frequent  examination  of  all  laboratory  notes  by  the 
teacher  is  also  essential  to  good  work,  and  the  proper  status 
of  the  notebook  work  can  be  secured  only  by  giving  it  a 
definite  proportion  in  the  marking  of  the  pupil's  work. 
A  rubber  stamp  with  the  word  " Approved"  and  the  in- 
structor's name  may  be  obtained  of  any  stationer  at  small 
expense  and  will  facilitate  the  work  of  correction  greatly. 
Neatness  as  well  as  accuracy  and  adequacy  of  report 


METHOD   OF   EXPERIMENT  5 

should  receive  proper  weight  in  the  marking  of  notebook 
work. 

When  the  work  is  completed  the  student  should  prepare 
an  index  of  drawings,  records  of  experiments,  and  descrip- 
tions of  demonstrations  contained  in  the  notebook.  It  is 
well  to  indicate  in  this  index,  after  each  title,  whether  the 
work  was  done  by  the  pupil  or  observed  and  recorded  by 
him,  and  whether  in  the  laboratory  or  as  home  work. 

The  following  directions  may  prove  of  value  as  indicating 
a  satisfactory  method  of  arrangement  of  a  notebook  record: 

A.  Record  the  number  and  date  of  the  exercise. 

B.  Make  drawings  of  the  apparatus  used,  when  neces- 

sary, and  label  them  properly. 

C.  State  as  briefly  as  possible: 

(1)  What  was  done. 

(2)  What  happened  as  the  results. 

(3)  What  meaning  these  results  have,  and  the 

purpose  of  the  exercise. 

D.  Answer  all  questions  in  the  text  and  try  to  condense 

your  statements  into  as  concise  and  brief  form  as 
possible. 

The  exercises  as  a  rule  should  precede  the  text  study  and 
serve  as  a  basis  for  such  study. 


TABLE  OF  CONTENTS 

Required  topics  are  indicated  by  a  star  (*);   the  others  are  optional. 

CHAPTER  PAGE 

PRELIMINARY  EXERCISES. 

I.  GLASS  BENDING  AND  CUTTING    ...      9 
II.  COLLECTION  OF  GASES        .         .         .         .10 

INTRODUCTORY  EXERCISES  IN  PHYSICS  AND  CHEMISTRY. 

*III.  PROPERTIES  OF  PHOSPHORUS       .         .  .12 

*IV.  PROPERTIES  OF  SULPHUR     .         .         .  .13 

*V.  PROPERTIES  OF  CARBON      .         .         .  .14 

*VI.  PROPERTIES  OF  IRON         .         .         .  .16 

*VII.  OXYGEN  AND  OXIDATION     .        .        .  .16 

*VIII.  PROPERTIES  OF  OXYGEN      .        .        .  .18 

*IX.  COMPOSITION  OF  AIR  AND  PROPERTIES  OF 

NITROGEN        .        .        .        .     .  %  .     20 

X.  COMPOSITION  OF  WATER      .        •         .  .21 

XI.  PROPERTIES  OF  HYDROGEN         .-         .  .23 

*XII.  ACIDS,  BASES,  SALTS,  AND  NEUTRALIZATION    24 

STUDY  OF  NUTRIENTS. 

*XIII.  PROTEIDS  .       .  .        .      .".  '      .         .     26 

*XIV.  CARBOHYDRATES — STARCH  .         .         .28 

*XV.  CARBOHYDRATES — GRAPE  SUGAR         .         .     28 

*XVI.  FATS  AND  OILS 29 

XVII.  MINERAL  SALTS 30 

XVIII.  WATER        .         .        .        .        .        .        .30 

STUDY  OF  FOODS. 

*XIX.  NECESSITY  OF  FOOD 32 

*XX.  NUTRIENTS  PRESENT  IN  COMMON  FOODS     .     33 
*XXI.  STUDY  OF  FOOD  CHARTS     .        .        .        .34 

6 


TABLE    OF  CONTENTS  7 

CHAPTER  PAGE 

HlSTOLOGICAL   STUDIES. 

*XXII.  PARTS  OF  A  CELL 36 

*XXIIL  STUDY  OF  A  PLANT  CELL     .         .         .         [37 
*XXIV.  STUDY    OF    LIVING    PROTOPLASM — AMGEBA     38 

XXV.  EPITHELIAL  TISSUE 42 

XXVI.  CONNECTIVE  TISSUE  .         .        .         .43 

XXVII.  MUSCULAR  TISSUE 45 

XXVIII.  NERVOUS  TISSUE        .        .        .        .        !     46 

PRINCIPLES  OF  DIGESTION. 

*XXIX.  PRINCIPLES  OF  OSMOSIS      .        .        .        .47 

*XXX.  AN  ENZYME 49 

*XXXI.  A  FERMENT  ORGANISM— YEAST         .        .     50 
*XXXII.  STRUCTURE  OF  A  TYPICAL  GLAND        .        .     51 

ORGANS  AND  PROCESSES  OF  DIGESTION. 

*XXXIII.  DISSECTION  OF  RAT'S  DIGESTIVE  ORGANS  53 

*XXXIV.  THE  TEETH 55 

XXXV.  PREPARATION  OF  DIGESTIVE  FLUIDS   .         .  57 

*XXXVI.  DIGESTION  OF  THE  MOUTH — SALIVA           .  58 
*XXXVII.  DIGESTION    OF    THE    STOMACH — GASTRIC 

JUICE 60 

XXXVIII.  DIGESTION  OF  THE  INTESTINE — PANCREATIN 

AND  BILE 62 

XXXIX.  DIGESTION  OF  MINERAL  SALTS    .         .        .64 

XL.  TABULATION  OF  NUTRIENT  DIGESTION        .  65 

XLI.  MICROSCOPIC  ANATOMY  OF  DIGESTIVE  TRACT  66 

BLOOD. 

*XLII.  GENERAL  PROPERTIES  OF  BLOOD        .        .    67 
*XLIII.  STUDY  OF  BEEF  OR  PIG  BLOOD      .         .        .69 

CIRCULATION  AND  THE  BLOOD  SYSTEM. 

*XLIV.  PROPERTIES  AND  LOCATION  OF  ARTERIES 

AND  VEINS 

*XLV.  CIRCULATION  IN  A  FROG'S  FOOT  .     73 

XLVI.  MINUTE    STRUCTURE    OF    ARTERIES    AND 

VEINS      ...  -74 

*XLVII.  STRUCTURE  OF  THE  HEART  .     75 


TABLE   OF  CONTENTS 

CHAPTER  PAGE 

THE  BODY  SKELETON. 

*XLVIII.  STUDY  OF  THE  SKELETON     .         .  .  .80 

*XLIX.  GROSS  STRUCTURE  OF  BONES       .  .  .80 

L.  COMPOSITION  OF  BONE        .         .  .  .82 

*LL  STRUCTURE  OF  A  JOINT       .         .  .  .82 

*LIJ*.  FORMS  OF  JOINTS 83 

MUSCLES  AND  MOTION. 

*LIIL  DISSECTION  OF  THE  MUSCLES      .  .  .84 

*LIV.  GROSS  STRUCTURE  OF  MUSCLE     .  .  .85 

LV.  NERVE  MUSCLE  PREPARATION     .  .  .86 

LVI.  STUDY  OF  LEVER  ACTION     .         .  .  .87 

LVII.  LEVERS  OF  THE  BODY        .        .  .  .89 

RESPIRATION. 

*LVIII.  DISSECTION  OF  A  RAT'S  LUNGS  .  .     90 

*LIX.  MECHANICS  OF  RESPIRATION       .  .  .91 

*LX.  STUDY  OF  EXPIRED  AIR       .         .  .  .91 

EXCRETION. 

LXI.  STUDY  OF  A  LAMB'S  KIDNEY       .  .  .93 

*LXII.  STUDY  OF  THE  SKIN     .     --  -r        .  .  .94 

NERVOUS  SYSTEM. 

*LXIII.  DISSECTION  OF  SHEEP'S  BRAIN  .  .     97 

*LXIV.  DISSECTION  OF  SPINAL  CORD       ..  .  .101 

SPECIAL  SENSES. 

*LXV.  NERVE  ACTION  .        .        .        .  .  .103 

*LXVI.  CUTANEOUS  SENSATIONS     .        .  .  .  104 

*LXVIL  STUDY  OF  THE  TONGUE       .        .  .  .  104 

*LXVIII.  SENSATIONS  OF  TASTE  AND  SMELL       .  .  105 

LXIX.  HEARING;  LAWS  OF  SOUND         .  .  .  105 

*LXX.  VISION;  DISSECTION  OF  SHEEP'S  EYE  .  106 

*LXXI.  ACTION  OF  THE  EYE 108 

BACTERIA. 

*LXXII.  STUDY  OF  BACTERIA  .111 


EXPERIMENTAL  PHYSIOLOGY 
AND  ANATOMY 

PRELIMINARY   EXERCISES 

I. — GLASS  BENDING  AND  CUTTING  (OPTIONAL). 

Apparatus. — Several  pieces  of  quarter  inch  glass  tubing  about  two 
feet  in  length,  a  three-cornered  file,  a  Bunsen  burner  with  fish-tail 
attachment. 

Directions. — A.  Bending.  Place  the  fish-tail  attach- 
ment on  the  burner  and  light  the  gas.  Hold  at  the  ends 
the  tube  which  is  to  be  bent  and  bring  into  the  flame  the 


FIG.  1. 


part  at  which  you  wish  the  bend  (see  Fig.  1).  Turn  the  tube 
constantly  to  insure  equal  heating  of  all  parts,  and  when 
the  glass  is  flexible  remove  from  the  flame  and  bend  the 
two  ends  slowly  toward  one  another  until  the  desired  angle 
is  obtained.  Use  care  to  keep  the  two  ends  in  the  same 
plane,  and  do  not  bend  quickly,  as  that  would  cause  buck- 

9 


10 


EXPERIMENTAL   PHYSIOLOGY 


ling.     If  the  glass 'cools  too  soon  return  it  to  the  flame  and 
treat  as  before. 

B.  Cutting.  Wet  the  file  and,  holding  the  tube  firmly 
with  finger  and  thumb,  make  a  slight  scratch  across  it. 
Turn  the  tube  over  and  repeat  the  operation  at  a  point 
directly  opposite.  Now  grasp  the  tube  in  both  hands,  one 
on  each  side  of  the  scratches,  and  bend  sharply.  The  result 
should  be  a  clean,  square-ended  break.  The  edges  may  be 
rounded  by  holding  them  in  the  flame  a  moment. 


II. — COLLECTION  OF  GASES  (OPTIONAL). 

Apparatus. — Pneumatic  trough  and  support,  glass  tube  bent  at 
right  angles,  large-mouthed  bottles,  piece  of  glass  to  cover  mouth  of 
bottle. 

Directions.— A  Fill  the  trough  with  water  to  the  depth 

of  a  half  inch  above  the 
top  of  the  support.  Fill 
the  bottle  with  water, 
cover  the  mouth  with 
the  glass,  and  invert, 
putting  the  mouth  under 
the  water  of  the  trough. 
Remove  the  piece  of 
glass,  and  place  the  bot- 
tle over  one  of  the 
holes  of  the  support. 
Does  the  water  flow  out? 
Explain. 

Now     introduce      the 
short  end    of   the   glass 
tube  into  the  mouth  of  the  bottle  (see  Fig.  2)  and  blow 


PRELIMINARY    EXERCISES 


11 


through  the  other  end.  Where  does  this  gas  go?  Why? 
Would  this  method  of  collecting  gases  be  successful  if  they 
were  readily  soluble  in  water? 

B.  Fill  a  second  bottle  with  water  and  invert  in  the  same 
way  as  the  first.  Bring  the  one  containing  the  gas  under 
the  one  containing  the  water,  and  gradually  turn  it  mouth 
upward  (see  Fig.  3).  In  this  way  gases  may  be  transferred 
from  one  vessel  to  another  for  study. 


FIG.  3. 


INTRODUCTORY    EXERCISES    IN    PHYSICS    AND 
CHEMISTRY 

III. — PROPERTIES  OF  PHOSPHORUS. 

Apparatus.— Piece  of  yellow  phosphorus,  evaporating  dish,  forceps, 
knife. 

Directions. — (Caution!  Phosphorus  should  be  kept  un- 
der water  and  cut  under  water.  It  should  not  be  allowed 
to  come  in  contact  with  the  bare  skin.) 

Fill  the  evaporating  dish  with  water  and  with  the  forceps 
place  the  piece  of  phosphorus  in  it.  With  the  knife  cut  off 
a  piece  and  examine  the  cut  surface.  Does  it  cut  easily? 
Describe  its  consistency.  What  color  is  the  new  cut  sur- 
face? Leave  this  exposed  to  the  light  for  a  time,  keeping 
it  under  water,  and  note  any  change  in  color.  Is  phos- 
phorus soluble  in  water? 

Pick  up  a  piece  with  the  forceps,  wipe  dry  with  filter  or 
blotting  paper,  and  hold  in  the  air  a  moment.  Describe 
what  takes  place.  Why  is  phosphorus  kept  under  water? 
Does  phosphorus  give  off  any  odor? 

Rub  phosphorus  gently  on  a  piece  of  paper  and  examine 
the  paper  afterwards  in  the  dark.  What  evidence  have  you 
that  phosphorus  burns  at  a  low  temperature? 

(Bone  is  the  part  of  the  body  richest  in  phosphorus.) 

Make  a  list  of  the  properties  of  phosphorus  so  far  as  you 
have  observed  them. 

12 


INTRODUCTORY   EXERCISES  13 

IV. — PROPERTIES  OF  SULPHUR. 

Apparatus. — Half  a  teaspoonful  of  flowers  of  sulphur  or  a  piece 
of  stick  sulphur,  a  silver  spoon,  a  hard-boiled  egg,  a  raw  egg,  an 
evaporating  dish,  alcohol  lamp  or  Bunsen  burner. 

Directions.— Examine  a  little  of  the  sulphur.  Has  it 
any  odor?  taste?  color?  Shake  some  up  in  water.  Does 
it  dissolve? 

Place  a  little  in  the  dry  evaporating  dish  and  heat 
gently.  Does  it  melt?  Describe  its  condition.  Continue  to 
heat  and  describe  the  various  changes  through  which  it 
passes. 

Touch  a  match  to  a  little  dry  sulphur.  Does  it  burn? 
Describe  the  result.  Smell  of  the  fumes  (Caution!).  Where 
have  you  noticed  this  odor  before?  (This  odor  is  due  to 
a  gas  called  an  oxide  of  sulphur  and  this  gas  is  formed  when- 
ever sulphur  is  burned.) 

Place  a  little  of  the  sulphur  in  the  bowl  of  .the  silver 
spoon.  After  a  moment  brush  it  off.  Is  the  silver  still 
bright?  (When  silver  is  brought  in  contact  with  sulphur 
the  latter  unites  with  it  and  forms  a  compound  called 
sulphide  of  silver,  which  is  black.) 

Mince  the  hard-boiled  egg  with  the  handle  of  the  silver 
spoon.  What  happens?  Compare  with  above  result.  (The 
two  stains  are  identical  and  the  latter  indicates  the  presence 
of  sulphur  in  eggs.) 

Place  the  raw  egg  in  a  clean  evaporating  dish  and  leave 
in  a  warm  place  for  several  days.1  When  the  egg  decays 
note  the  odor.  (This  odor  is  due  to  another  compound  of 

1  It  is  well  to  place  the  dish  in  a  closed  vessel  containing  a  little  water,  as 
otherwise  the  egg  may  dry  up  without  decaying. 


14  EXPERIMENTAL   PHYSIOLOGY 

sulphur  called  hydrogen  sulphide.  When  animal  flesh  de- 
cays it  gives  off  this  odor,  showing  that  flesh  contains  sul- 
phur.) 

Mention  seven  properties  of  sulphur  which  you  have  ob- 
served in  the  above  experiments. 


V. — PROPERTIES  OF  CARBON. 

Apparatus. — Stick  of  wood-charcoal,  bottle  with  a  small  mouth, 
limewater, x  glass  tube  six  or  eight  inches  long,  beaker,  test  tubes, 
splinter  of  wood,  piece  of  meat,  piece  of  marble,  hydrochloric  acid. 

Directions. — Examine  the  charcoal  stick.  (Charcoal  is 
one  of  the  forms  of  carbon.)  What  is  its  color?  odor?  taste? 
Does  it  dissolve  in  water? 

Light  the  stick,  after  trimming  it  to  such  a  size  as  to  enable 
it  to  be  thrust  through  the  neck  of  the  bottle.  Does  it  give 
off  any  odor  in  burning?  Is  it  like  or  unlike  sulphur  in  this 
respect? 

Thrust  the  lighted  stick  of  charcoal  into  the  bottle  and 
keep  it  there  until  the  flame  goes  out.  Now  remove  it  and 
cover  the  mouth  of  the  bottle  with  the  finger.  Can  you  see 
anything  in  the  bottle?  Take  a  drop  of  clear  lime  water 
in  the  end  of  the  glass  tube  and  hold  it  in  the  air  a  few 
minutes.  Is  there  any  change  in  the  limewater?  Now 
introduce  it  into  the  bottle  without  touching  the  sides  of 
the  bottle.  What  happens  to  the  color  of  the  limewater? 
What  sort  of  substance  must  be  present  in  the  bottle? 
(When  carbon  burns  it  forms  a  gaseous  compound  with  the 
oxygen  of  the  air  called  an  oxide  of  carbon  or  carbonic  acid 

1  Limewater  may  be  made  by  slaking  a  little  quicklime  in  water  and  de- 
canting the  clear  liquid. 


INTRODUCTORY   EXERCISES  15 

gas.  This  gas  is  the  only  one  that  will  cause  the  change  in 
lime  water  noted  above.) 

Rinse  out  the  bottle  with  water.  Light  the  wood  splinter 
and  thrust  into  the  bottle.  Proceed  as  with  the  charcoal 
Test  the  contents  of  the  bottle  with  a  drop  of  lime- 
water.  What  evidence  have  you  that  wood  contains 
carbon? 

Burn  the  piece  of  meat  by  heating  it  in  the  test  tube. 
Suspend  a  drop  of  limewater  in  the  tube  by  means  of  the 
glass  tube.  What  evidence  have  you  that  animal  flesh 
contains  carbon? 

Place  the  piece  of  marble  in  a  clean  test  tube.  Pour  on  it 
a  little  hydrochloric  acid  which  has  been  diluted  previously 
with  twice  its  volume  of  water.  What  evidence  of  action* 
have  you?  Hold  suspended  a  drop  of  limewater  in  the  mouth 
of  the  tube.  Hydrochloric  acid  and  water  contain  no  car- 
bon ;  what  must  you  conclude  as  to  the  presence  of  carbon 
in  the  marble? 

(Carbon  is  to  be  found  in  all  animal  and  vegetable  com- 
pounds and  in  some  minerals.) 

Pour  some  of  the  limewater  into  the  beaker.  By  means 
of  the  glass  tube  blow  some  of  your  breath  through  the 
liquid  in  the  beaker.  In  what  form  is  the  carbon  in  your 
breath?  (Expired  air  contains  about  4  parts  of  this  gas  in 
every  100  parts  of  the  expired  air.  Ordinary  air  contains 
about  .04  part  of  this  gas  in  100  parts,  or  about  4  parts  in 
every  10,000  parts  of  air.) 

(Besides  charcoal,  the  other  forms  of  carbon  are  diamond 
and  graphite.  All  the  forms  of  carbon  are  odorless,  taste- 
less, and  insoluble  in  water;  and  if  strongly  heated  in  the 
presence  of  oxygen,  each  form  of  carbon  will  combine  with 
it  and  form  carbonic  acid  gas.) 


16  EXPERIMENTAL   PHYSIOLOGY 

VI. — PROPERTIES  OF  IRON. 

Apparatus. — Several  feet  of  fine  wrought-iron  wire,  a  magnet,  an 
evaporating  dish. 

Directions. — Bring  the  magnet  in  contact  with  the  iron. 
Raise  the  magnet.  Note  that  the  iron  is  attracted  to  it. 
See  if  other  things  are  similarly  attracted  to  it. 

Place  a  coil  of  the  wire  in  a  warm,  dry  place.  Place  a  like 
coil  in  the  evaporating  dish  and  cover  with  water.  Leave 
both  coils  for  several  days,  and  then  examine  them.  Note 
that  one  of  them  is  covered  withva  reddish  deposit  (rust). 
What  conditions  are  favorable  to  this  formation?  (Rust 
is  a  compound  that  iron  forms  with  the  oxygen  of  air  and 
Water.  It  is  this  power  of  iron  to  unite  with  oxygen  that 
makes  it  valuable  as  a  part  of  the  blood  in  the  animal  body; 
see  Exercise  XL/Ill,  D,  on  page  71.) 

VII. — OXYGEN  AND  OXIDATION. 

Apparatus. — Red  oxide  of  mercury  (mercuric  oxide),  test  tube, 
stick  of  charcoal,  limewater  and  glass  tube,  alcohol  lamp  or  Bunsen 
burner. 

Directions. — Place  in  a  test  tube  as  much  red  oxide  as 
you  can  get  on  your  finger  nail.  Heat  the 
test  tube  in  the  flame  (see  Fig.  4).  Heat 
the  end  of  the  charcoal  stick  until  it  glows, 
and  introduce  it  into  the  mouth  of  the 
test  tube.  After  heating  the  oxide  hot  you 
will  notice  a  change  in  the  glow  of  the 
charcoal.  Describe  it.  Can  you  see  any- 
thing in  the  tube?  If  it  be  a  colorless 
FIG.  4.  gag  ^a^  -g  ac£mg  on  tne  charcoal  can  that 

gas  be  air?    Reasons  for  your  statement? 


INTRODUCTORY   EXERCISES  17 

Remove  the  tube  from  the  flame.  When  the  stick  ceases 
to  glow  remove  it  and  substitute  for  it  a  drop  of  limewater 
on  the  end  of  the  glass  tube.  What  happens?  What  does 
this  indicate?  As  the  tube  cools  what  do  you  see  on  the 
sides  of  the  tube?  Do  you  know  the  name  of  this  sub- 
stance? 

EXPLANATION.  Oxide  of  mercury  is  a  compound  of  mer- 
cury (quicksilver)  and  oxygen.  Heat  decomposes  this  into 
oxygen  and  mercury.  In  what  form  were  these  two  sub- 
stances given  off  in  the  above  experiment?  We  have  al- 
ready learned  that  when  charcoal  burns  it  forms  a  gas  called 
carbonic  acid  gas.  How  was  this  formed  in  the  above 
exercise?  We  can  express  the  above  actions  in  the  form  of 
equations  as  follows: 

(1)  Oxide  of  mercury  +  heat  =  oxygen  and  mercury. 

(2)  Oxygen  +  carbon  +  heat  =  oxide  of  carbon  +  heat. 
In  chemical  language  the  process  illustrated  in   (1)  is 

analysis,  or  the  separation  of  a  compound  into  its  parts. 
The  process  illustrated  in  (2)  is  synthesis,  or  the  union  of 
parts  to  make  a  compound.  All  chemical  actions  may  be 
grouped  under  one  or  the  other  of  these  processes. 

The  special  kind  of  compound  that  results  from  the  union 
of  oxygen  with  a  substance  is  called  a  compound  of  oxida- 
tion, and  the  actual  formation  is  called  oxidation.  When 
oxidation  takes  place  rapidly,  light  and  heat  are  produced 
at  the  same  time  and  the  process  is  called  rapid  oxidation 
or  combustion.  Give  examples  from  your  experience  of  both 
kinds  of  oxidation — the  slow  and  the  rapid.  Why  does  the 
exclusion  of  air  from  a  fire  cause  the  fire  to  go  out?  What 
is  the  precise  action  of  water  or  sand  when  thrown  on  a 
flame,  in  the  light  of  the  above  explanation? 


18 


EXPERIMENTAL   PHYSIOLOGY 


VIII. — PROPERTIES  OF  OXYGEN. 


Apparatus. — Chlorate  of  potash  (potassium  chlorate),  manganese 
dioxide,  piece  of  phosphorus,  stick  of  charcoal,  sulphur,  fine  iron  wire, 
Florence  flask,  one-holed  rubber  stopper,  rubber  and  glass  connect- 
ing tubing,  wash  bottle  fitted  with  two-holed  stopper,  ring  stand, 
sand  bath,  pneumatic  trough,  five  large-mouthed  glass  bottles  with 
glass  plates  to  cover,  caustic  soda,  Bunsen  burner  or  alcohol  lamp, 
deflagrating  spoon. 

Directions. — Set  up  the  apparatus  as  in  Fig.  5.    Place 


FIG.  5. 

in  the  flask  to  a  depth  of  half  an  inch  a  mixture  of  one  part 
of  manganese  dioxide  to  four  parts  of  chlorate  of  potash. 
Fill  the  wash  bottle  about  half  full  of  water  and  dissolve 
a  stick  of  caustic  soda  in  it.1  When  everything  is  connected 
as  in  the  diagram  heat  the  flask  gently  on  the  sand  bath. 
The  first  of  the  gas  produced  will  mix  with  the  air  in  the 

1  This  will  absorb  the  impurities  in  the  oxygen. 


INTRODUCTORY   EXERCISES  19 

apparatus,  and  should  be  allowed  to  escape.  When  the 
bubbles  of  gas  flow  freely  through  the  delivery  tube,  fill 
one  of  the  bottles  with  water  and  invert  over  the  delivery 
tube  to  receive  the  gas  (oxygen)  as  in  the  above  diagram 
(see  Exercise  II  on  page  10).  When  the  bottle  is  full  cover 
with  the  glass  plate  and  set  aside  mouth  upward.  Fill  the 
other  four  bottles  in  the  same  way.  Then  proceed  as  fol- 
lows: 

A.  Examine  the  gas  in  the  first  bottle.    Has  it  any  color? 
odor?    Suck  a  little  into  the  mouth  with  a  glass  tube.    Has 
it  any  taste? 

B.  Tie  a  piece  of  charcoal  to  the  handle  of  the  deflagra- 
ting spoon,  heat  the  end  of  the  charcoal  until  it  glows,  and 
introduce  it  into  the  second  bottle.    Describe  the  result. 
Keep  lowering  the  charcoal  as  it  tends  to  stop  burning,  until 
it  reaches  the  bottom  of  the  bottle.    Compare  this  result  with 
that  of  Ex.  VII.    What  name  do  you  give  to  this  process? 
How  could  you  test  the  contents  of  the  bottle  to  prove  your 
statement?    Do  so  and  record  result  (see  Ex.  VII). 

C.  Place  in  the  bowl  of  the  deflagrating  spoon  a  piece 
of  phosphorus  the  size  of  a  pea  (Caution!  Handle 

with  forceps  and  cut  under  water).  Light  the 
phosphorus  and  introduce  quickly  into  the  third 
bottle.  Describe  the  result.  Does  it  burn  more  or 
less  brilliantly  than  in  air?  Note  the  white  cloud 
in  the  bottle.  (This  is  an  oxide  of  phosphorus  and 
is  formed  by  the  uniting  of  the  phosphorus  and 
the  oxygen.)  Compare  this  result  with  that  in  B. 

D.  After  cleaning  the  deflagrating  spoon  place 
some  powdered  sulphur  in  it.    Light  the  sulphur. 

Note  how  it  burns  in  air  and  the  color  of  the  flame.    FlQ-  6- 
Now  introduce  it  into  the  fourth  bottle.     Describe  the  re- 


20 


EXPERIMENTAL   PHYSIOLOGY 


suit.  After  the  burning  is  over  smell  (Caution!)  the  gas 
in  the  bottle.  Compare  with  the  odor  of  burning  sulphur 
in  Ex.  IV.  What  is  the  name  of  this  gas?  Is  the  action 
noted  above  combustion?  Give  your  reasons  (see  Ex.  VII.) 

E.  Heat  the  end  of  the  fine  iron  wire  red  hot  and  intro- 
duce it  into  the  fifth  bottle.  Describe  the  result.  After 
the  action  is  over  examine  the  red  spots  on  the  sides  of  the 
bottle  and  compare  them  with  the  rust  obtained  in  Ex.  VI. 
What  is  the  difference  between  the  two  actions? 

Name  the  properties  of  oxygen  that  you  have  observed. 


IX. — COMPOSITION  OF  Am  AND  PROPERTIES  OF  NITROGEN. 

Apparatus. — Pneumatic  trough,  bell  jar  closed  at  the  top,  evap- 
orating dish,  test  tube,  phosphorus. 

Directions. — Fill  the  pneumatic  trough  so  as  just  to  cover 
the  support.  Place  the  evaporating  dish  on  the  support. 
Place  in  it  a  piece  of  phosphorus  the  size  of  a  pea;  light  the 
phosphorus,  and  cover  quickly  with  the  bell  jar. 

A.  Note  the  white  fumes  that 
appear.  What  are  these?  (See 
Ex.  VIII,  0.)  What  is  one  of 
the  components  of  air?  When 
the  jar  is  first  put  on  note  that 
some  bubbles  are  forced  out  be- 
cause the  heat  causes  the  air  to 
expand  a  little.  The  phosphorus 
stops  burning  when  all  the  oxygen 
FlG<  7-  in  the  bell  jar  is  used  up.  Let 

the  apparatus  stand  until  the  white  oxide  of  phosphorus  has 
been  absorbed  by  the  water  and  the  gas  in  the  jar  is  clear. 


INTRODUCTORY   EXERCISES  21 

(Phosphorus  was  used  instead  of  sulphur  or  charcoal  in  this 
exercise  because  its  oxide  is  a  solid  which  settles  and  dis- 
solves in  the  water.)  Has  the  water  risen  in  the  jar? 
What  part,  by  volume,  of  the  jar  does  it  occupy?  Since 
the  phosphorus  has  used  up  all  the  oxygen  in  burning,  about 
what  part  of  air  mast  be  oxygen? 

B.  Fill  the  test  tube  with  gas  from  the 'bell  jar  in  the 
manner  described  in  Ex.  II,  B.  Examine  this  gas.  What 
is  its  color?  odor?  taste?  Place  a  lighted  match  in  it. 
What  happens?  Explain.  (This  gas  is  called  nitrogen.1) 
Of  what  advantage  is  the  presence  of  nitrogen  in  the  air? 
Why  is  a  good  draught  necessary  to  make  a  fire  burn  freely? 
If  the  body  needs  to  take  in  oxygen  constantly  why  can 
we  not  live  in  a  sealed  room? 


X.  —  COMPOSITION  OF  WATER  (OPTIONAL). 

Apparatus.  —  Electrolysis  apparatus,2  sulphuric  acid,  four  dry 
cells,  splinters  of  wood,  test  tubes,  pneumatic  trough  or  other  dish 
of  water,  glass  and  rubber  connecting  tubing. 

Directions.  —  Open  the  two  stopcocks  and  fill  the  ap- 
*paratus  with  water  con  taming  5%  of  sulphuric  acid.  When 
the  tubes  are  full  and  all  air  driven  out,  close  the  cocks;  ar- 
range the  four  dry  cells  in  series  (positive  pole  of  one  con- 
nected with  negative  pole  of  the  next,  and  so  on);  and 
connect  the  positive  and  negative  poles  of  the  series  with  the 


gases   (carbonic  acid  gas,  argon,  water  vapor)  are  present  in  very 
small  proportions. 

2  For  the  electrolysis  apparatus  shown  on  p.  22  may  be  substituted  simpler 
forms  with  nearly  as  good  results.  Simple  forms  are  shown  in  Clark  and 
Dennis's  "  Elementary  Chemistry,"  page  33;  and  in  Remsen's  "  Chemistry, 
Briefer  Course," 


22 


EXPERIMENTAL   PHYSIOLOGY 


posts  as  indicated  in  Fig.  8.  Note  what  happens.  Where  do 
the  bubbles  form?  In  which  tube  do  they  form  most  rapidly? 
What  is  the  ratio  by  volume  of  the 
gases  in  the  two  tubes? 

When  the  tube  containing  the  most 
gas  is  full,  disconnect  the  cells.  Collect 
in  a  test  tube  the  gas  from  the  tube 
containing  the  lesser  amount  as  follows: 
With  rubber  connecting  tubing  connect 
an  ordinary  delivery  tube,  filled  with 
water,  to  the  top  of  the  gas  tube. 
Insert  the  end  of  the  delivery  tube 
into  the  mouth  of  the  test  tube,  after 
filling  the  test  tube  with  water  and  in- 
verting as  in  Ex.  II.  Open  the  cock 
and  collect  the  gas  as  in  Fig.  9.  Cover 
the  mouth  of  the  tube  with  the  thumb 
and  hold  mouth  upward.  Now  re- 
move the  thumb  and  quickly  insert  a  lighted  splinter  into 
this  collected  gas.  What  happens?  What  gas  have  you 

studied  that    produces  a 


FIG.  8. 


This 


is 


similar  action? 
the  same  gas. 

In  a  second  test  tube 
collect  the  gas  in  the 
other  tube.  Hold  it 
mouth  downward,  and 
introduce  a  lighted  splin- 
ter into  it.  Describe 

what  happens.     How  is  this  gas  different  from   oxygen? 

from  nitrogen?     (The   name  of   this  new  gas  is  hydrogen. 

The  electric  current  has  broken  the  compound — water— 


FIG.  9. 


INTRODUCTORY   EXERCISES 


23 


into  its  two  parts,  hydrogen  and  oxygen.)    Is  this  exercise 
synthesis  or  analysis? 


XI. — PROPERTIES  OF  HYDROGEN   (OPTIONAL). 

Apparatus. — Granulated  zinc  or  pieces  of  sheet  zinc,  dilute  sul- 
phuric acid,1  bottle  with  two-holed  stopper,  thistle  tube,  glass  and 
rubber  connecting  tubing,  pneumatic  trough,  large-mouthed  bottle, 
test  tubes. 

Directions. — Set  up  the  apparatus  as  in  the  diagram. 
Place  a  handful  of  zinc  in  the  bottle  and  pour  on  enough 
dilute  sulphuric  acid  through  the  thistle  tube  to  cover  the 
zinc.  (Caution!  Keep  all 
flames  away  from  the  ap- 
paratus until  the  gas  is  col- 
lected.) Let  this  gas  escape 
until  it  is  bubbling  freely 
from  the  delivery  tube ;  then 
collect  the  large  bottle  full 
through  water  as  in  Ex. 
VIII.2 

A.  By  the  method  of  Ex. 
II,  B,  take  some  of  the  gas 

in  a  test  tube  and  examine  it,  holding  the  test  tube  mouth 
downward.     Has  it  any  color?  odor?  taste? 

B.  Collect  a  second  test  tube  full  and  hold  mouth  down- 
ward as  before.     Tie  a  match  to  a  wire,  light  the  match,  and 
thrust  it  up  into  the  tube.     Does  the  match  continue  to 

1  To  dilute  sulphuric  acid,  pour  slowly  one  part  of  acid  into  five  or  six  parts 
of  water.     Stir  while  pouring. 

2  The  gas  will  be  freer  of  impurities  if  passed  through  a  wash  bottle  c 
taining  permanganate  solution. 


FIG.  10. 


24  EXPERIMENTAL   PHYSIOLOGY 

burn?  Reason?  Where  does  the  hydrogen  burn?  Why? 
After  the  hydrogen  has  burned  up,  examine  the  sides  of 
the  tube.  What  do  you  find  on  them?  Why  should  you 
expect  this?  What  is  oxide  of  hydrogen? 

C.  Hold  a  fresh  test  tube  full  of  hydrogen  mouth  upward 
for  a  few  moments.  At  the  end  of  that  time  test  with  a 
match.  Is  the  hydrogen  still  there?  Explain.  (Hydro- 
gen is  the  lightest  substance  known.) 

XII. — ACIDS,  BASES,  SALTS,  AND  NEUTRALIZATION. 

Apparatus. — Dilute  hydrochloric  and  nitric  acids  (one  part  acid 
to  ten  parts  water),  caustic  soda,  red  and  blue  litmus  paper,  evapo- 
rating dish,  glass  stirring  rod,  Bunsen  burner. 

Directions. — A.  Examine  some  of  the  dilute  hydrochloric 
acid.  What  sort  of  an  odor  has  it?  Describe  its  taste. 
Rub  some  between  the  fingers;  describe  its  "feel."  Dip 
a  piece  of  red  litmus  into  it.  What  is  the  effect?  i)ip  in 
a  piece  of  blue  litmus.  Describe  the  result.  (The  taste, 
"feel,"  and  effect  on  litmus  noted  are  three  ways  in  which 
you  can  detect  any  acid.)  Test  some  common  substances 
and  record  results;  e.  g.,  cream  of  tartar,  vinegar,  soda, 
fruit  juices,  ammonia. 

B.  Dissolve  a  stick  of  caustic  soda,  an  .inch  long,  in  a 
tumbler  of  water.     Examine  this  liquid.     What  is  its  taste? 
odor?  "feel"?    Test  it  with  the  two  kinds  of  litmus  paper 
and  record  results.     (This  kind  of  substance  is  called  a  base. 
Bases  always  react  in  this  way  to  taste,  "feel, "  and  litmus. 
Certain  strong  bases  are  called  alkalis.)    Test  the  substances 
named  in  A.    Which  of  these  are  bases? 

C.  Pour  some  of  the  caustic  soda  solution  into  the  evap- 
orating dish.    Add,  gradually,  the  dilute  hydrochloric  acid, 


INTRODUCTORY   EXERCISES  25 

stirring  with  the  rod  and  testing  with  the  litmus  until  the 
solution  turns  neither  red  litmus  blue,  nor  blue  litmus  red. 
If  too  much  acid  is  added  correct  it  with  more  basic  solu- 
tion. The  acid  and  the  base  are  now  said  to  be  neutralized, 
and  the  process  is  called  neutralization.  Evaporate  this 
mixture  to  dryness  over  the  flame.  What  sort  of  substance 
is  left  in  the  dish?  Taste  it.  Is  it  familiar?  Does  it  affect 
litmus  in  the  solid  state  or  when  dissolved  in  water? 

D.  Repeat  the  above  neutralization,  using  nitric  acid 
instead  of  hydrochloric.  Does  the  product  affect  litmus? 

(The  products  of  C  and  D  are  called  neutral  salts.  To  this 
class  of  substances  belong  most  of  the  minerals  of  the 
earth.)  This  exercise  may  be  continued  with  other  acids 
and  bases  at  the  desire  of  the  experimenter. 


STUDY  OF  NUTRIENTS 

Phosphorus,  sulphur,  carbon,  iron,  oxygen,  nitrogen,  and 
hydrogen  are  a  few  of  the  chemical  elements  to  be  found  in 
plant  and  animal  bodies.  These  elements  occur,  however, 
not  as  elements,  but  in  combinations,  or  compounds.  There 
are  many  of  these  combinations,  but  they  may  be  grouped 
together  under  a  few  class  names.  These  classes  of  com- 
pounds show  certain  definite  qualities  by  means  of  which 
their  presence  may  be  detected.  The  classes  are  called  proxi- 
mate principles,  or  nutrients.  The  most  important  are: 

Proteids,  or  nitrogenous  compounds. 

Carbohydrates,  or  starches  and  sugars. 

Fats  and  oils. 

Mineral  salts.      •' 

Water. 

XIII. — PROTEIDS. 

Apparatus. — Raw  white  of  egg,  olive  oil,  salt,  nitric  acid,  ammonia, 
Millon's  reagent,1  caustic  soda,  sulphate  of  copper  (blue  vitriol),  test 
tubes. 

Directions. — A.  Put  a  little  white  of  egg  (a  good  example 
of  proteid)  in  a  test  tube,  cover  with  two  inches  of  water, 
and  shake.  Does  the  white  of  egg  dissolve?  Heat  the 

1  To  make  Millon's  reagent,  mix  one  part  of  mercury  by  weight  with  two 
parts  of  nitric  acid  (concentrated  commercial) ;  when  the  mercury  is  all  dis- 
solved, dilute  with  twice  the  volume  of  water. 


STUDY   OF   NUTRIENTS  27 

water  and  egg  mixture  slowly.  What  form  does  the  white 
of  egg  take  now?  Is  this  form  soluble  in  water? 

Put  a  second  portion  of  the  egg  in  a  test  tube.  Add 
dilute  nitric  acid  to  it.  What  happens  to  the  white  of  egg? 
Compare  the  action  with  that  in  boiling  water.  * 

(This  action  of  acid  and  heat  on  a  proteid  like  egg  albu- 
min is  called  coagulation.}  Why  does  a  piece  of  meat 
(which  is  composed  mainly  of  a  proteid  like  white  of  egg) 
become  more  solid  under  heat? 

B.  Xanthoproteic  Test.    Place  a  little  coagulated  white  of 
egg  in  a  test  tube  and  cover  with  dilute  nitric  acid.     Heat 
to  boiling  and  then  add  enough  ammonia  to  neutralize  the 
acid  and  give  an  alkaline  test.    The  white  of  egg  (proteid) 
takes  what  color?    Treat  in  the  same  way  some  olive  oil, 
some  common  salt,  and  any  other  substance  that  does  not 
contain  proteid.     Do  any  of  these  take  the  same  color  as 
the  white  of  egg? 

C.  Milton's  Test.    Add  enough  Millon's  reagent  to  a  little 
coagulated  white  of  egg  to  cover,  and  boil.    What  color  does 
the  egg  and  the  solution  become?    Treat  the  other  sub- 
stances mentioned  in  B  in  the  same  way.     Do  they  act  like 
the  egg? 

D.  Biuret  Test,  or  Piotrowski's  Reaction.    Add  caustic  soda 
in  concentrated  solution  to  some  white  of  egg,  in  a  test  tube. 
To  this  add  a  few  drops  of  a  solution  of  copper  sulphate. 
What  color  do  you  get?    Boil.    What  change  takes  place 
in  the  color?    Test  other  substances  mentioned  in  B  in  the 
same  way. 

(Of  the  three  chemical  tests  for  proteid  given  above,  the 
xanthoproteic  is  best  for  general  use.  There  are  many 
forms  of  proteid,  but  these  tests  will  indicate  its  presence 
whatever  its  form  may  be.) 


28  EXPERIMENTAL   PHYSIOLOGY 

XIV. — CARBOHYDRATES — STARCH. 

Apparatus. — Solution  of  iodine,1  laundry  starch,  white  of  egg, 
olive  oil,  test  tubes. 

Directions. — Place  a  little  starch  in  a  test  tube  and  fill 
the  tube  a  quarter  full  of  water.  Shake  it.  Does  the 
starch  dissolve?  Boil;  what  happens  to  the  starch? 

Put  a  little  of  the  starch  paste  in  a  test  tube  with  an 
inch  of  water.  Boil.  Now  add  a  drop  of  the  solution  of 
iodine.  What  color  does  the  paste  become? 

Test  a  little  white  of  egg  and  olive  oil  (which  contain  no 
starch)  in  the  same  way.  Do  you  get  the  same  result? 

(This  test  will  indicate  the  presence  of  starch,  whatever 
may  be  its  form.) 

XV. — CARBOHYDRATES — GRAPE  SUGAR. 

Apparatus. — Fehling's  solution^  raisins,  starch,  oil,  test  tubes. 

Directions. — Mince  the  raisins,  cover  with  water  in  a  test 
tube,  and  let  stand  until  the  grape  sugar  (glucose  or 
dextrose)  has  dissolved.  Put  a  little  of  the  clear  solu- 
tion in  a  second  test  tube  and  dilute  it  with  double  its 
volume  of  water.  Add  a  few  drops  of  Fehling's  solution 
and  heat  to  boiling.  When  no  further  change  in  color 

1  To  make  the  iodine  solution,  dissolve  a  teaspoonful  of  potassium  iodide 
crystals  in  a  tumbler  of  water.     Add  crystals  of  iodine  and  stir  until  a  rich 
wine  color  is  obtained.     This  may  be  bottled  and  used  as  needed. 

2  To  make  Fehling's  solution: 

A.  Dissolve  35  grams  of  copper  sulphate  in  500  c.c.  of  water.     Label  this 
solution  (A). 

B.  Dissolve  160  grams  of  caustic  soda  and  173  grams  of  Rochelle  salts  in 
500  c.c.  of  water.     Label  this  solution  (B). 

Keep  these  two  solutions  separate  until  ready  for  use.  Prepare  for  test 
by  mixing  equal  -quantities. 


STUDY  OF  NUTRIENTS 


takes  place,  note  the  final  color.  Test  in  the  same  way  oil, 
starch,  and  any  other  substance  that  contains  no  grape 
sugar.  Compare  results. 

(This  is  a  universal  test  for  grape  sugar.) 


XVI.— FATS  AND  OILS. 

Apparatus.— Flaxseed  (ground),  beef  fat,  unglazed  paper,  ben- 
zine, filter  paper,  glass  funnel,  evaporating  dish,  chemical  ther- 
mometer. 

Directions. — A.  Put  a  little  beef  fat  in  the  evaporating 
dish  and  heat.  When  it  begins  to  melt  stir  with  the  chemi- 
cal thermometer  and  note  the  temperature  of  the  melting 
point.  If  the  body  temperature  is  98°  F.  what  does  this 
experiment  indicate  as  to  the  condition  of  fats  in  the  body? 
Name  some  fats  that  are  liquid  at  ordinary  temperatures. 

B.  Place  a  little  beef  fat  on  the  unglazed  paper   and 
warm.     Remove   and  examine   the  paper.     How  does  it 
show  the  presence  of  fat?     Substitute  for  the  beef  fat  a 
little  ground  flaxseed  and  repeat  the  above  process.     Does 
flaxseed  act  like  beef  fat?    Do  starch  and  other  substances 
which  contain  no  fat  or  oil,  act  in  the  same  way?     (The 
above  is  a  general  test  for  fats  and  oils  in  whatever  form 
they  may  be.) 

C.  Place  a  teaspoonful  of  ground  flaxseed  in  the  evapo- 
rating  dish   and    cover  with  benzine.     (Ether  will  act  in 
the  same  way.)     Cover  the  dish  and  allow  it  to.  stand  for  a 
few  hours.     At  the  end  of  that  time,  filter  off  the  benzine 
by  means  of  the  funnel  and  filter  paper,  into  a  clean  evapo- 
rating dish.     Allow  this  dish  of  filtered   benzine  to  stand 
for  a  time  until  all  the  benzine  has  evaporated.    What  is 


30  EXPERIMENTAL   PHYSIOLOGY 

left  in  the  dish?  What  did  the  benzine  do  to  the  fat  in  the 
flaxseed?  Treat  sugar  or  anything  else  that  contains  no  fat 
or  oil  in  the  same  way.  Is  the  result  the  same?  (The 
above  method  is  another  test  for  fat  or  oil.) 


XVII. — MINERAL  SALTS  (OPTIONAL). 

Apparatus. — Platinum  foil  or  piece  of  sheet  iron,  forceps,  piece 
of  meat  or  vegetable  matter. 

Directions. — Place  the  meat  on  the  foil  and  hold  the 
foil  in  the  flame  with  the  forceps  until  all  the  black  has 
disappeared  from  the  burning  meat.  The  residue  is  min- 
eral matter.  Would  this  test  be  possible  if  this  mineral 
matter  were  combustible?  What  color  is  the  residue? 
(This  is  the  test  for  determining  the  presence  and  amount 
of  mineral  salts.) 


XVIII.— WATER  (OPTIONAL). 

Apparatus. — Pieces  of  parsnip,  potato,  apple,  lettuce  leaves,  flour, 
meal,  meat,  test  tube,  balance  sensitive  to  one  gram. 

Directions. — A.  Heat  one  of  the  above  substances  in  a 
dry  test  tube.  As  the  tube  cools  after  having  been  taken 
from  the  flame,  examine  the  sides  and  note  what  you  see 
on  them.  In  what  form  was  the  water  before  the  tube  was 
cooled? 

B.  Weigh  a  portion  of  each  of  the  above  substances,  re- 
cord the  weights,  and  place  the  substances  in  a  warm,  dry 
place  for  a  few  days.  Then  weigh  again  and  record  as  be- 
fore. Continue  this  until  there  is  no  further  decrease  in 


STUDY    OF   NUTRIENTS  31 

weight.  The  loss  of  weight  represents  approximately  the 
water  contained  in  the  substances  before  it  evaporated. 
From  your  results  answer  the  following  questions:  About 
what  per  cent  of  water  did  each  substance  contain?  Why 
are  flour  and  grains  in  general  a  good  food  for  travelers  to 
carry?  Why  are  fruits  and  salads  good  hot-weather  foods? 


STUDY  OF  FOODS 


XIX. — NECESSITY  OF  FOOD. 

Apparatus. — Wide-mouthed  bottles,  corks  to  fit,  pea  or  corn  seed- 
lings, nutrient  solution,1  test  tubes,  paraffin  wax,  distilled  water. 

Directions.  A.  Take  one  of  the  pea  or  corn  seedlings  and 
cut  off  the  cotyledons  close  to  the  stem. 
Pass  this  through  a  hole  in  one  of  the 
corks,  and  insert  in  a  bottle  as  shown 
in  Fig.  11.  Fill  the  bottle  about  three 
quarters  full  of  the  nutrient  solution. 
Prepare  a  second  seedling  in  the  same 
way  (select  one  of  as  near  the  same  size 
as  possible),  but  substitute  distilled 
water  for  the  nutrient  solution.  Note 
the  growth  of  each  seedling  for  several 
days.  *Do  they  grow  equally  fast? 
What  sort  of  food  is  in  the  nutrient  solu- 
tion? From  the  composition  of  the 
water  and  the  mineral  salts,  is  it  possible  for  the  plant  to 
get  its  carbon  from  the  nutrient  solution?  (Air  contains  a 
small  proportion  of  carbonic  acid  gas  [see  Ex.  V]  and  plants 

iNutrient  Solution  after  Sachs  ('82). 

Distilled  water  (H2O) 1000.00    c.c. 

Potassium  nitrate  (KNOs) 1-00    gram 

Sodium  chloride  (NaCl) 0.50 

Calcium  sulphate  (CaSO*) 0. 50 

Magnesium  sulphate  (MgSO4) 0.50 

Calcium  phosphate  (Ca3  [PO^) 0. 50 

Ferric  chloride  (FeCl3) 0.005 

(Do  not  put  the  ferric  chloride  into  the  solution  in  the  first  place,  but  add 
a  drop  of  it  to  each  bottle  when  the  seedlings  are  put  in.) 

32 


FIG.  11. 


STUDY   OF   FOODS 


33 


secure  their  carbon  through  their  leaves,  which  absorb  the 
gas  from  the  air.)  From  your  observations  can  a  plant 
live  indefinitely  on  water  alone? 

B.  Seal  the  growing  seedling  of  A  to  the  cork  with  melted 
paraffin  wax,  cover  the  upper  part  of  the  seedling  with  a 
test  tube,  and  seal  the  edges  of  the  tube  to  the  cork.     Does 
the  plant  continue  to  live?     (Plants  can  not  live  without 
air.)     What  collects  on  the  inside  of  the  tube?    What  evi- 
dence have  you  that  a  plant  gives  off  water? 

C.  Prepare  a  third  and  a  fourth  seedling  as  in  A.    In  one 
bottle  put  some  nutrient  solution  made  without  the  potas- 
sium nitrate,  and  in  the  other  the  normal  solution.    Which 
seedling  lives  longest?     (To  support  life,  one  food  required 
by  plants  is  some  nitrogen  salt  like  potassium  nitrate.) 

D.  Prepare  a  fifth  seedling  as  in  A,  using  a  nutrient  so- 
lution with  only  the  ferric  chloride  omitted.    After  several 
weeks,  notice  the  effect  on  the  color  of  the  plant. 


XX. — NUTRIENTS  PRESENT  IN  COMMON  FOODS. 

Apparatus. — Meat,  flour,  milk,  parsnip,  lettuce,  peanuts,  and  the 
necessary  materials  for  the  tests  described  in  Exs.  XIII  to  XVIII. 

Directions. — Apply  the  tests  to  each  substance  separately 
and  tabulate  your  results  as  follows: 


TEST 

RESULT 

NUTRIENT    PRESENT 

RELATIVE  AMOUNT 

Xanthoproteic 

Biuret 

Millon's 

Iodine  sol. 

Fehling's 

Unglazed  paper 

Benzine 

Dry  test  tube  &  heat 

Platinum  foil  &  heat 

34 


EXPERIMENTAL  PHYSIOLOGY 


Under  " Result"  tell  exactly  what  happens. 

Under  "Nutrient  Present"  write  the  name  of  the  nutri- 
ent that  the  test  shows  to  be  present.  If  no  reaction  fol- 
lows from  the  test  leave  this  space  blank. 

Under  " Relative  Amount"  write  Little  if  the  reaction  is 
weak,  and  Much  if  the  reaction  is  strong. 

From  your  results,  why  are  flour,  meat,  and  milk  consid- 
ered especially  valuable  foods? 


XXI. — STUDY  OF  FOOD  CHARTS.1 


FOOD 

COMPOSITION  %  OF  NUTRIENTS 

Energy  in 
Calories 
per  Pound 

Average 
Cost 
per  Pound 

Proteid 

Starch 

Other 
Carbo- 
hydrate 

Fat 

Water 

Mineral 

Bread  (White) 

8. 

47. 

3. 

1. 

37. 

2. 

1280. 

$.04 

Flour 

11. 

66. 

4.2 

2. 

15. 

1.7 

1645. 

.025 

Oatmeal 

12.6 

58. 

5.4 

5.6 

15. 

3. 

1850. 

.05 

Rice 

6. 

79. 

0.4 

0.7 

13. 

0.5 

1630. 

.07 

Beans 

23.1 

55. 

2. 

2. 

12.6 

3.1 

1615. 

.05 

Potatoes 

2. 

18. 

3. 

0.2 

76. 

0.7 

375. 

.0125 

Milk 

4. 

— 

5.0 

4.0 

86. 

0.8 

325. 

.035 

Cheese 

28.3 

— 

1.8 

35.5 

30.2 

4.2 

2070. 

.16 

Beef  (Round) 

20.5 

— 

— 

10.1 

68.2 

1.2 

805. 

J4 

Beef  (Corned  Flank) 

14.2 

— 

— 

33. 

49.8 

3. 

1655. 

.10 

Mutton  (Leg) 

18.3 

— 

— 

19. 

61.8 

0.9 

1140. 

.18 

Veal  (Shoulder) 

20.2 

— 

— 

9.8 

68.8 

1.2 

790. 

.20 

Pork  (Shoulder—  fresh) 

16. 

— 

— 

32.8 

50.3 

0.9 

1680. 

.16 

Pork  (Ham) 

16.7 

— 

— 

39.1 

41.5 

2.7 

1960. 

.16 

Pork  (Salt  Fat) 

0.9 

— 

— 

82.8 

12.1 

4.2 

3510. 

.12 

Chicken 

24.4 

— 

— 

2.0 

72.2 

1.4 

540. 

.20 

Eggs 

14.9 

— 

— 

10.5 

73.8 

0.8 

721. 

.18 

Butter 

1. 

— 

0.5 

85. 

10.5 

0.3 

3615. 

.30 

Cod  fish 

15.8 

— 

— 

0.4 

82.6 

1.2 

310. 

.08 

Mackerel 

18.2 

— 

— 

7.1 

73.4 

1.3 

640. 

.12 

Oysters 

6. 

— 

3.7 

1.2 

87.1 

2. 

230. 

.25 

1  More  extensive  tables  may  be  found  in  a  pamphlet  printed  by  the  Depart- 
ment of  Agriculture,  Farmer's  Bulletin  No.  23,  "Foods,  Nutritive  Value  and 
Cost,"  by  W.  O.  Atwater. 


STUDY   OF   FOODS 


35 


DIETARY  STANDARDS. 


CONDITIONS 

PROTEID  ' 

CAHBO- 

HYDRATES 

FAT 

CALORIES 

Man  with  light  muscular  exercise. 
Man  with  moderate    " 
Man  with  active  muscular  work. 

0.22  Ibs. 
0.28  Ibs. 
0.33  Ibs. 

0.88  Ibs. 
0.99  Ibs. 
01.10  Ibs. 

0.22  Ibs. 
0.28  Ibs. 
0.33  Ibs. 

2980. 
3520. 
4060. 

Questions  to  be  answered  from  study  of  Food  Chart. 

Fat  and  carbohydrates  are  the  energy  producers:  how 
does  the  table  show  this?  What  sorts  of  foods  are  richest 
as  proteid  furnishers  (tissue  builders)?  Of  the  animal  and 
vegetable  foods,  which  are  richest  in  proteid?  fat?  carbo- 
hydrates? 

Calculate  the  cost,  amount  of  energy  in  calories,  and  per 
cent  of  nutrients,  in  the  following  daily  dietaries : 

(a)  13  ounces  of  beef  (round),  3  ounces  of  butter,  6  ounces 
of  potatoes,  22  ounces  of  bread. 

(b)  4  ounces  of  salt  pork,  2  ounces  of  butter,  16  ounces 
of  beans,  8  ounces  of  bread. 

(c)  10  ounces  of  beef  (corned),  1  ounce  of  butter,  16  ounces 
of  milk  (pint). 

Make  up  a  suitable  daily  dietary  for  each  of  the  three 
different  classes  of  men  given  in  the  table. 


HISTOLOGICAL   STUDIES 


XXII. — PARTS  OF  A  CELL. 

Apparatus. — Scalpel,  compound  microscope1  with  two-thirds  and 
one-sixth  inch  objectives  and  one  inch  ocular,  glass  slides  and  cover 
glasses,  piece  of  filter  paper,  methyl  green  or  Delafield's  haema- 
toxylin.2 

Directions. — Sterilize  the  scalpel  by  holding  it  in  boiling 

water,  then  scrape 
the  inside  of  the 
cheek  lightly  with 
the  blade.  When 
the  scalpel  is  re- 
moved from 
mouth  there 
appear  on  it 
scrapings  in 

e  r 

FIG.  12. — A,  diagram  of  a  cell;  w,  cell  wall  with  inclosed 

cytoplasm;  n,  nucleus,  consisting  of  nuclear  membrane    S  6  CL 1  m  6  n  t . 
inclosing   granular  substance,    in    which   are    seen 
spherical  nucleolus  and  irregular  masses  of  chromatin; 


a,  centrosome;  B-F,  changes  that  take  place  during 
cell  division. 


the 
will 
the 
the 

a  white 
Re- 
move   a   little    of 
this  sediment  and 


mount  in  a  drop 
of  water  on  the  slide.  Cover  with  the  cover  slip  and  ex- 
amine with  the  two-thirds  objective  (low  power).  In  focus- 

1  Bausch  &  Lomb  and  the  Spencer  Lens  Co.  furnish  at  request  a  pamphlet 
describing  all  the  parts  of  the  microscope  and  method  of  handling  the  instru- 
ment. 

2  For  the  preparation  of  these  stains  consult  any  manual  of  microscopy. 
Lee's  "Vade  Mecum"  is  recommended. 


HISTOLOGICAL  STUDIES  37 

ing,  the  best  results  are  obtained  if  nearly  all  the  light  is 
excluded  by  the  diaphragm. 

Draw  what  you  see.  Note  that  the  masses  are  made  up 
of  separate  elements  (cells).  Compare  with  Fig.  12,  A. 
Are  the  walls  circular  as  in  the  figure? 

Place  a  drop  of  the  methyl  green  at  one  side  of  the  cover 
slip  and  by  placing  the  filter  paper  at  the  opposite  side  draw 
this  solution  under  the  slip.  Let  the  slide  stand  for  a  mo- 
ment and  examine  again  with  the  low  power.  What  part 
of  the  cell  has  changed  color?  (This  part  is  called  the  nu- 
cleus of  the  cell.) 

Now  focus  on  one  of  these  cells  with  the  one-sixth  ob- 
jective (high  power).  Has  the  cell  a  definite  outline?  Note 
the  clear  liquid  between  the  nucleus  and  the  outline.  Do 
you  notice  any  particles  floating  in  this  liquid?  Draw  this 
cell,  magnified  to  an  inch  diameter,  and  label  as  follows :  the 
outside  boundary,  or  cell  wall-  the  clear  liquid,  or  protoplasm; 
the  particles  floating  in  this  protoplasm,  or  granules;  the 
nucleus. 

XXIII.— STUDY  OF  A  PLANT  CELL. 

Apparatus.— Pond  scum  (Spirogyra),  normal  salt  solution,1  ma- 
terials described  in  Ex.  XXII. 

Directions.— Mount  a  little  of  the  pond  scum  in  a  drop 
of  water  and  cover  with  a  glass.  Examine  with  the  low 
power.  Do  you  see  any  separate  units  in  this  case?  How 
are  they  arranged?  What  is  their  color?  Is  this  color 
evenly  distributed  throughout  the  cell  or  located  in  definite 
parts  of  the  cell?  Can  you  see  any  cell  wall?  protoplasm? 

1  Normal  salt  solution  is  made  by  adding  six-tenths  of  one  per  cent  of 
common  salt  (NaCl)  to  distilled  water. 


38  EXPERIMENTAL   PHYSIOLOGY 

nucleus?  Make  a  drawing  of  what  you  see  and  label  in  such 
a  way  as  to  answer  the  above  questions. 

Now  add  a  little  of  the  normal  salt  solution,  to  be  run 
under  the  cover  glass,  and  examine  with  the  high  power.  Do 
you  see  any  nucleus  now?  any  protoplasm?  What  has  hap- 
pened to  the  protoplasm?  Draw  and  label  such  parts  of 
the  cell  as  show.  A  little  methyl  green  or  Delafield's  hsem- 
atoxylin  added  will  make  the  nucleus  more  distinct. 

Make  a  list  of  the  differences  and  similarities  between  the 
cells  examined  in  Ex.  XXII  and  Ex.  XXIII. 

NOTE. — The  comparison  of  cells  should  be  further  demonstrated 
with  other  materials  by  the  instructor,  until  the  essential  and  varia- 
ble components  are  clearly  grasped  by  the  pupil.  Some  suggested 
material:  Pleurococcus,  potato,  diatoms,  root  tips,  etc. 

XXIV. — STUDY  OF  LIVING  PROTOPLASM — AMCEBA. 

Apparatus. — About  a  month  beforehand  collect  the  leaves  and 
sediment  from  pools  of  still,  but  clear  water.  Distribute  this  mate- 
rial— together  with  a  few  water  plants  (Nitella  or  Chara) — in  sev- 
eral open,  shallow  dishes.  Keep  covered  with  water.  When,  in 
course  of  time,  the  water  in  these  has  become  clear  and  free  from 
scum,  take  up  with  a  pipette  (medicine  dropper)  some  of  the  sedi- 
ment from  the  very  surface  of  the  leaves.  Examine  this  for  amoebae 
with  the  low  power  (two-thirds  objective).  When  the  dish  contain- 
ing them  in  quantity  is  located,  mark  this  for  supply.1  The  other 
apparatus  is  the  same  as  in  Ex.  XXII. 

Directions. — Mount  some  of  the  amoebae  on  a  glass  slide, 
and  cover  them  with  a  cover  slip.  Locate  one  of  the  animals 

*A.  W.  Weysse  of  Boston  University  gives  in  "Science,"  Vol.  XX,  No.  515, 
the  following  method  of  securing  amoeba.  Collect  a  considerable  number 
of  lily  pads.  Remove  with  a  spatula  the  slime  which  adheres  to  the  lower 
surface  and  put  it  in  a  shallow  glass  aquarium  containing  water  six  or  eight 
centimeters  deep.  Place  the  vessel  near  a  window  and  in  a  week  or  two 
amosbae  will  be  abundant  on  the  surface  of  the  sediment  at  the  bottom. 


HISTOLOGICAL  STUDIES  39 

with  the  low  power  and  then  focus  on  it  with  the  high  power 
for  careful  observation. 

Watch  the  amoeba  until  it  begins  to  show  movement,  then 
draw  and  note  the  following  parts:  round,  opaque  nucleus, 


B 


FIG.  13.— A,  Amoeba  proieus:  a,  food  vacuole;  c,  contractile  vacuole;  ec,  ectoplasm; 
en,  endoplasm;  n,  nucleus;  v,  water  vacuoles.     B,  Amoeba  radiosa. 

the  clear  outer  part  (ectoplasm)  and  the  granular  inner  part 
(endoplasm)  of  the  cytoplasm.  (Cytoplasm  is  the  name  given 
to  that  part  of  the  protoplasm  which  is  not  nuclear,  since 
the  nucleus  is  also  composed  of  protoplasm.)  Note,  further, 


40  EXPERIMENTAL   PHYSIOLOGY 

the  round  spots  in  the  cytoplasm  (vacuoles:  food  vacuoles, 
water  vacuoles,  or  contractile  vacuoles,  according  to  con- 
tents) ;  the  constantly  forming  projections  of  the  cytoplasm 
(pseudopodia) ;  and  the  absence  of  any  cell  wall. 

(Amoeba  is  a  one-celled  animal  made  up  of  free  protoplasm 
and  hence  well  suited  to  show  the  properties  of  this  sub- 
stance, which  is  the  physical  basis  of  all  life.) 

Properties  of  Protoplasm. 

A.  What  color  is  the  cytoplasm?    Does  it  appear  thicker 
or  thinner  than  the  water?     Is  the  part  containing  granules 
of  the  same  color  as  the  clear  part?     Does  this  cytoplasm 
mix  with  the  water?    Describe  the  appearance  of  the  nu- 
cleus. 

B.  Movement.    Watch  the  moving  amoeba.     Note  the  va- 
rious steps  in  the  forming  of  a  pseudopodium.     Is  the  move- 
ment of  the  animal  rapid?    Does  it  appear  to  move  in  a 
definite  direction  or  at  random?    Do  the  particles  in  the 
water  appear  to  affect  its  movement?    Press  on  the  cover 
glass  with  a  needle  point  just  above  the  amoeba.     How  does 
the  amoeba  react?    Note  that  the  movement  of  the  amoeba 
is  produced  as  a  result  of  two  properties  of  protoplasm, 
contraction  and  expansion.     A  substance  having  these  prop- 
erties is  said  to  have  contractility. 

C.  In  B  we  noted  that  the  animal  contracted  and  ex- 
panded without  apparent  cause  in  some  cases.     We  noted 
also  that  under  pressure  it  contracted  more  strongly.    This 
power  to  respond  to  special  stimuli  is  called  irritability. 
Test  the  irritability  of  the  protoplasm  toward  heat,  by  ap- 
plying the  flame  of  an  alcohol  lamp  gently  to  the  end  of 
the  glass  slide.     Record  your  observations  as  the  heat  grad- 


H1STOLOGICAL  STUDIES  41 

ually  increases.     Other  tests  may  be  made  by  running  so- 
lutions of  various  salts,  etc.,  under  the  slide. 

D.  Feeding  Habits.    Examine  the  contents  of  some  of  the 
vacuoles  and  state  your  conclusions  as  to  the  form  of  food 
taken  in  by  the  protoplasm.     Note  and  describe  the  method 
of  ingulfing  these  food  particles  and  the  forming  of  the 
vacuole.     Compare  several  of  these  vacuoles  as  to  the  con- 
dition of  their  contents.    From  these  observations,  what  do 
you  conclude  happens  to  food  in  the  amoeba? 

(The  process  of  taking  in  food  is  called  ingestion.  The 
process  of  dissolving  ingested  food  is  called  digestion.  The 
process  of  transforming  digested  food  into  protoplasm  is 
called  assimilation.  This  last  process  is  evidenced  by  the 
decreasing  size  of  the  vacuole  after  the  food  is  dissolved.) 

E.  The  Removal  of  Wastes.    Study  the  action  of  the  large 
contractile  vacuole.    What  does  it  appear  to  contain  when 
expanded?    Where  does  this  substance  come  from?    Where 
does  it  go  when  the  vacuole   is    contracted?      Does    the 
vacuole  pulsate  regularly? 

(The  process  of  collecting  the  broken-down  waste  of  the 
body  and  its  removal  to  the  outside  is  called  excretion. 
The  processes  described  in  D,  by  means  of  which  pro- 
toplasm is  made,  are  spoken  of  collectively  as  anabolism. 
The  processes  by  means  of  which  old  protoplasm  is  broken 
down  and  removed  are  spoken  of  collectively  as  katabolism. 
Metabolism  is  the  simultaneous  occurrence  of  these  two  ac- 
tions in  a  living  body  of  protoplasm.) 

F.  Place  several  amoebae  in  a  drop  of  water  in  a  vial  and 
cork  the   vial   tightly.    The  water  used  should  be  rich  in 
food — bacteria.     Also,  for  comparison,  make  a  balance  prep- 
aration consisting  of  the  same  number  of  amoebae  mounted 
in  the  same  amount  of  water  in  a  watch  glass,  this  prepara- 


42 


EXPERIMENTAL  PHYSIOLOGY 


tion  to  be  exposed  to  the  air  in  a  large  vessel  containing  a 
little  water  to  prevent  evaporation.  Examine  at  the  end 
of  a  few  days.  What  evidence  have  you  that  protoplasm 
requires  air? 

(It  is  the  oxygen  in  the  air  that  the  animal  uses.  This 
property  of  taking  in  air  and  oxygen  is  part  of  a  process 
called  respiration.) 

Make  a  list  of  all  the  properties  of  protoplasm  as  exhib- 
ited by  the  cytoplasm  of  the  amoeba. 


XXV.  —  EPITHELIAL  TISSUE  (OPTIONAL). 

Apparatus.  —  Prepared  slide1  of   cross  section  of  the  small  intes- 
tine (human  preferred,  but  rat's  or  other  mammal's  will  serve),  com- 

pound microscope. 

Directions  —  Focus 
with  the  high  power 
on  the  cells  forming 
the  inner  layer  of  the 
intestine.  Draw  six 
or  eight  of  these  cells, 
showing  the  large  nu- 
cleus in  each,  the  gen- 
eral  outline  of  the 

Epithelial  Tissues,     a,  two  forms  of  epithelial  tissue:         -i-i  j    ,-1         -j.    ,    .-, 

1,   columnar;    2  and  3,  squamous;   c,  stratified    Cells>   and  tn^  OlStnbU- 
tissue;  6,  simple   ciliated  tissue;  d,  ciliated  col- 
umnar  tissue. 


14. 


FIG.  15. 


Of  the  protoplasm. 
A 

Note  the   thinness   of 
the  cell  wall  and  the  absence    of  intercellular   material. 

1  Prepared  slides  for  study  of  tissues  may  be  bought  best  of  dealers,  as 
their  preparation  is  a  matter  of  delicacy  and  skill.  For  those  who  wish  to 
prepare  their  own,  suitable  directions  will  be  found  in  standard  histologies, 
such  as  Stohr's  or  Schafer's,  and  in  Lee's  "Vade  Mecum." 


HISTOLOGICAL  STUDIES 


43 


Compare  these  cells  (columnar  epithelium;  see  Fig.  15,  d) 
with  those  of  Ex.  XXII  (squamous  epithelium;  see  Fig.  14, 
a,  2  and  3,  and  c).  How  do  they  differ?  Note  the  pro- 
tective character  of  these  layers  of  cells  with  reference  to 
the  underlying  layers.  (One  feature  of  this  protection  is 
prevention  of  the  action  of  digestive  fluids  upon  the  under- 
lying muscles  and  other  forms  of  tissue.) 


XXVI. — CONNECTIVE  TISSUE  (OPTIONAL). 

Apparatus. — Prepared  slides  of   intermuscular  tissue,  cartilage, 
and  bone,  compound  microscope. 

Directions. — A.  Intermuscular  Tissue.  Draw,  under  the 
low  power.  Note  two  classes  of  bundles  of  fibers  (white 
fibers  and  elastic).  The  elastic  fibers  are  single  and  are 
more  sharp  in  outline  than  the 
white.  Find  one  of  the  cells  (or 
corpuscles)  and  focus  with  the 
high  power.  Draw  it,  and  show 
in  your  drawing  its  relation  to 
the  two  classes  of  fibers.  From 
your  study,  which  part  of  this 
tissue  should  you  say  was  most 
important,  the  cellular  part  or 
the  intercellular  fibers? 

B.  Cartilage  (hyaline).  Note 
the  solid  character  of  the  in- 
tercellular matrix,  the  outlines 
of  the  cells  with  their  proto- 
plasm and  nucleus,  the  lacunce,  or  pits  in  which  the  cells 
lie,  and  the  capsules  inclosing  these  lacunse.  Which  part  of 


Corpuscle 


Bundle  of  White  Fibers 
FIG.  16. — Intermuscular  Tissue. 


44 


EXPERIMENTAL   PHYSIOLOGY 


this  tissue  is  supporting,  the  cells  or  the  matrix?    Draw  a 
section,  under. the  high  power,  and  label  all  parts. 

P»*W^^  C'  Bone-     Note    the  ma- 

trix of  spongy  bone  arranged 
in  concentric  rings  (lamellce) 
around  the  central  canals 
(Haversian  canals) .  Be- 
tween the  lamellae  note  the 

..L cnp  irregular    cavities     (lacunce) 

m  with  their  wavy  branches  or 
canaliculi.  Note  how  these 
canaliculi  connect  the  la- 
cunse  with  one  another  and 

FIG.  17. — Hyaline  Cartilage:    cap,  capsule; 

w,  matrix   formed   by   cells;  c,   cartilage    with    the    HaVerSian     Canals. 

Odl:  n'  nucleus'  Look  in  the  lacunaa  for  the 

bone  cells.     (In  ground  sections  of  bone  these  will  prob- 
ably be  wanting.    They  appear  better  in  sections  of  de- 


FIG.  18. — Bone:   a,  canaliculi;  6,  Haversian  canal;  c,   lacuna. 

calcified  bone.)     Draw,  under  high  power,  a  section   loca- 
ting all  the  above  named  parts. 


HISTOLOGICAL   STUDIES 


45 


(Note  in  the  three  classes  of  connective  tissue  that  the 
intercellular  portion  is  the  important  part  in  support.  The 
importance  of  the  cells  becomes  clear  when  it  is  understood 
that  this  intercellular  matrix  is  produced  by  them.) 

XXVII. — MUSCULAR  TISSUE  (OPTIONAL). 

Apparatus. — Prepared  slides  of  striated  and  non-striated  muscle, 
compound  microscope. 

Directions. — A.  Non-striated.  Note  the  long,  spindle- 
shaped  cells,  the  elongated  nucleus,  and  the  homogeneous 
protoplasm  filling  the  whole 
cell.  Note,  further,  how 

these  Cells  interlace.       (They      FlG-    19-~A  Non-striated  Muscle  Cell:   n, 

nucleus. 

are  held   together  by  a  ho- 
mogeneous cement  substance.)     Note  the  absence  of  any 
striation,  or  striping.     Draw  several  of   these  cells    under 
the  high  power,  locating  all  the  parts  mentioned  above. 

B.  Striated.  Examine  a  single  fiber  with  the  high  power. 
Note  the  broad,  dim,  transverse  striae 
and  the  narrow,  light,  transverse  striae. 
The  broad  stria  is  called  anisotropic  or 
doubly  refracting,  contractile  sarcoplasm. 
The  narrow  stria  is  called  isotropic  or 
singly  refracting  sarcoplasm.  Note  also  the 
more  or  less  dim  longitudinal  striation. 
Over  the  whole  of  the  fiber  is  stretched  the 
transparent  sarcolemma,  or  cell  wall.  Some- 
where on  the  fiber  may  be  found  also  sev- 
eral nuclei.  Draw  and  locate  all  these  parts  of  the  muscle 
cell.  ( Sarcoplasm  is  merely  another  name  for  the  protoplasm 
of  a  muscle  cell.) 


.  20.— 

striated      Muscle 

Fibers.   (The  figure 

shows  the  striae  and 


46 


EXPERIMENTAL   PHYSIOLOGY 


Dendrites. 


process 


Neurilemma 


XXVIII.  —  NERVOUS  TISSUE  (OPTIONAL). 

Apparatus.  —  Prepared  slides  of  ganglion  cells  and  nerve  fibers,  l 
compound  microscope. 

Directions.  —  A.  The*  Nerve 
Cell.  Note  the  irregular  out- 
line of  the  cell;  the  wavy  pro- 
jections, or  dendrites;  the  rod- 
]fae  projections,  or  nerve  proc- 
esses. Note  the  position  of  the 
nucleus.  Has  the  cell  one  or 
Axis  cylinder  more  nerve  processes?  Draw 
and  locate  all  parts,  under  the 
high  power. 

B.  The  Nerve  Fiber.  Make 
out  from  your  study  of  the 
nerve  fiber,  the  axis  cylinder 
in  the  center.  (This  corre- 
sponds to  the  nerve  process  of 
A.)  Next  outside  this  is  the 
medullary  sheath,  and  on  the 
very  outside  the  neurilemma. 
Make  a  drawing  showing  all 
these  parts.  For  their  relation 

FIG.  21—  Scheme   of   a    Neuron:    a,     pnTnnj,Tp 
free  axis  cylinder;    6,    axis  cylinder    ( 
surrounded   by  neurilemma  alone; 
c,     axis     cylinder    surrounded    by 
medullary     sheath  alone  ;     d,    axis 
cylinder  surrounded  by  the  sheath    be    placed    in  One    OI   the    aDOVC 


tisSU6S     of    the    body  Can 


classes — epithelial,     connective, 
muscular,  or  nervous. 

*A  smear  preparation  of  spinal  cord  may  be  prepared  as  follows:  Rub  a 
piece  of  fresh  spinal  cord  in  water  between  two  cover  glasses.  Mount  and 
run  under  the  cover  glass  a  drop  of  methyl  green.  Both  nerve  fibers  and 
nerve  cells  appear  ip  such  a  preparation, 


the  nodes  of  Ranvier). 


PRINCIPLES  OF  DIGESTION 


XXIX. — PRINCIPLES  OF  OSMOSIS. 

Apparatus. — Potassium  bichromate,  raisins,  white  of  egg,  starch, 
Fehling's  solution,  iodine  solution,  Millon's  reagent,  dialyzer.  There 
are  several  forms  of  dialyzer  described  by  different  authors,  any  one 
of  which  will  serve.  The  following  form  has  been  found  very  satis- 
factory. Obtain  from  the  butcher  some  skins  such  as  are  used  to 
hold  sausage  meat.  Tie  one  of  these 
around  the  base  of  a  student  lamp 
chimney  as  in  Fig.  22,  after  cutting 
off  the  chimney  so  that  it  is  only  about 
six  inches  in  height.  Select  a  cork  to 
fit  tightly  in  the  top  of  the  chimney 
and,  with  a  cork  borer,  puncture  this 
to  fit  an  eighth-inch  glass  tube  about 
a  foot  in  length.  Arrange  the  whole 
apparatus  as  in  the  diagram,  support- 
ing the  chimney  in  an  outer  jar  so 
that  it  will  not  rest  on  the  bottom. 
To  fill  the  chimney,  remove  the  cork 
and  tube.  The  tube  will  serve  as  a 
delicate  indicator  of  the  amount  of 
rise  in  the  water. 


FIG.  22. 


Directions. — A.  Put  into  the 
dialyzer  some  crystals  of  potas- 
sium bichromate.  Fill  with  water  both  the  dialyzer  and 
the  outer  jar  until  the  level  is  the  same  in  each.  Allow 
them  to  stand  for  a  short  time.  Then  examine  and  note  the 
level  of  water  in  the  two  parts.  What  has  been  the  pre- 
47 


48 


EXPERIMENTAL   PHYSIOLOGY 


vailing  direction  of  flow  of  the  water?  Is  the  color  of  the 
water  in  the  outer  jar  changed?  Has  some  of  the  salt  solu- 
tion in  the  dialyzer  passed  through  the  membrane?  (This 
interchange  of  water  and  salt  solution  through  a  non-porous 
membrane — the  sausage  skin — is  called  osmosis.) 

B.  Chop  up  some  raisins  and  place  in  a  beaker  with  some 
water.    When  the  grape  sugar  in  the  raisins  is  well  dis- 
solved, transfer  this  liquid  to  the  dialyzer.     Fill  both  dialyzer 
and  outer  jar  to  the  same  level  with  water  as  before.     Note 
the  direction  of  the  water-flow.    Test  the  water  in  the  outer 
jar  with  Fehling's  solution.     What  results?    Does  grape 
sugar   in  solution  pass    readily  through    the    membrane? 
(Substances  which  pass  readily  in  solution  through  a  mem- 
brane under  the  above  conditions  may  be  said  to  dialyze.) 

C.  Substitute  for  the  raisin  solution  a  diluted  starch  paste. 
After  a  tune  note  the  level  of  the  water.     Record  its  direc- 
tion of  flow.    Test  the  liquid  in  the  outer  jar  with  iodine 
solution.     Does  starch  dialyze?    Does  starch  crystallize  like 
grape  sugar  and  potassium  biehromate? 

D.  Substitute  for  the 
starch    paste    a  solution 
made    of  white     of    egg 
whipped    up    in   water. 
Note  direction  of  flow  of 
water.    Test  the  water  in 
the  outer  jar  with  MiUon's 
test  for    proteid.     Does 
egg  albumin  dialyze? 

E.  Cut    a    few   slices 
of  beet  root.     Wash  and 

place  a  few  pieces  in  two  separate  beakers.  Fill  each 
beaker  half  full  of  distilled  water.  Boil  the  slices  in  one 


FIG.  23. — A,  living  cell;  B,  cell  whose  proto- 
plasm has  been  killed  by  boiling;  cw,  cell 
wall;  n,  nucleus;  p,  protoplasm. 


PRINCIPLES   OF   DIGESTION  49 

of  the  beakers.  (This  kills  the  protoplasm  in  the  cells  of 
the  beets  without  injury  to  the  cell  walls.)  Add  a  few 
drops  of  hydrochloric  acid  to  each  beaker,  and  then  test 
with  Fehling's  solution  for  grape  sugar.  In  which  has  the 
sugar  dialyzed  from  the  cells?  In  which  is  the  water  col- 
ored? Study  the  arrangement  of  protoplasm  in  a  dead  and 
in  a  living  cell  as  illustrated  in  Fig.  23,  and  state  your 
conclusions  as  to  the  influence  of  protoplasm  on  dialysis. 

(Substances  that  dialyze  are  called  crystalloids.  Sub- 
stances that  do  not  dialyze  are  called  colloids.) 

XXX. — AN  ENZYME. 

Apparatus. — Ground  malt,  starch,  test  tubes,  iodine  solution, 
Fehling's  solution. 

Directions. — Make  an  extract  of  malt  diastase  (an  en- 
zyme) by  shaking  up  five  grams  of  ground  malt  with  50  c.c. 
of  cold  water.  Let  it  stand  for  a  few  hours  and  then  filter. 
Make  a  thin  starch  paste  by  mixing  a  teaspoonful  of  starch 
with  a  cup  of  boiling  water.  Fill  two  test  tubes  half  full 
of  this  starch  preparation.  Test  a  little  of  the  starch  prep- 
aration with  the  iodine  solution,  to  determine  strength  of 
reaction.  Test  a  little  of  the  starch  preparation  and  also 
some  of  the  diastase  solution  with  Fehling's  solution.  Is 
grape  sugar  present  in  either  of  them?  Now  add  10  c.c.  of 
diastase  solution  to  one  of  the  test  tubes;  heat  both  tubes, 
and  keep  them  as  near  as  possible  at  a  constant  temperature 
of  60°  centigrade. 

At  intervals  of  five  minutes  remove  a  little  of  the  con- 
tents of  each  tube  with  a  pipette  and  test  with  the  iodine 
solution.  Do  the  same,  using  Fehling's  solution  instead  of 
iodine  solution.  Is  the  amount  of  starch  on  the  increase 


50  EXPERIMENTAL   PHYSIOLOGY 

or  decrease  in  either  tube?  After  how  long  a  time  do  you 
get  a  test  for  grape  sugar,  and  in  which  tube?  Continue 
these  tests  until  you  get  a  strong  test  for  grape  sugar. 

(The  reason  for  these  results  is  that  the  malt  diastase — 
the  enzyme — is  slowly  changing  the  starch  into  sugar.  An 
enzyme  is  a  substance  which  can  bring  about  the  trans- 
formation of  one  chemical  compound,  such  as  starch,  into 
another,  such  as  sugar,  without  itself  being  used  up.  The 
value  of  enzyme  action  in  our  bodies  lies  in  the  fact  that 
by  it  a  colloid,  like  starch,  may  be  changed  into  a  crystalloid, 
like  sugar,  which  can  then  be  absorbed  through  a  membrane 
by  dialysis,  e.  g.,  from  the  stomach  through  the  walls  of  the 
blood  vessels  into  the  blood.) 

XXXI. — A  FERMENT  ORGANISM — YEAST. 

Apparatus. — Yeast  cake,  molasses,  eight-ounce  bottle,  absorbent 
cotton,  limewater,  chemical  thermometer. 

Directions. — Dissolve  a  piece,  of  yeast  cake,  the  size  of 
a  pea,  in  two  tablespoonfuls  of  water.  Pour  this  into  the 
eight-ounce  bottle.  Add  to  this  a  tablespoonful  of  mo- 
lasses and  fill  the  bottle  half  full  of  water.  Stopper  with 
a  plug  of  absorbent  cotton  and  leave  in  a  warm  place  for 
twenty-four  hours.  Record  the  temperature  of  the  room 
in  which  the  bottle  is  put,  and  the  temperature  of  the  mix- 
ture. 

At  the  end  of  the  twenty-four  hours  remove  the  stopper 
and  examine  the  contents.  What  is  the  temperature? 
Does  it  smell  sweet?  Test  the  gas  in  the  top  of  the  bottle 
with  a  drop  of  lime  water.  What  gas  gives  this  reaction? 
Does  the  odor  give  you  any  evidence  of  the  presence  of 
alcohol?  Examine  under  the  low  power  of  the  compound 


PRINCIPLES   OF   DIGESTION  51 

microscope  a  little  of  the  sediment  from  the  bottom  of  the 
bottle,  mounted  in  water.  Draw  several  groups  of  the 
separate  elements  of  this  sediment.  (These  bodies  are 
yeast  plants.) 

(Yeast  is  a  one-celled  plant  that,  with- 
out changing  its  yeast  character,  is  capa- 
ble of  transforming  sugar  into  carbonic 
acid  gas  arid  alcohol.  In  its  power  to 
change  a  substance,  without  itself  under- 
going transformation,  it  acts  like  an  en-  ^  9 
zyme  and  hence  is  called  a  ferment  organ-  FlG  2^—  Yeast  Plants: 


ism.     Many    digestive  actions    are  per-     1>  a  Plant 

c  bud;  2,  the  bud  near- 

IOrmed  either  by  enzymes  or  by  ferment  iy  ready  to  separate 

organisms,  with  results  like  that  noted  in  as  a  new  plant- 

Ex.  XXX.     Most  enzymes  are  produced  in  the  body  by 
organs  called  glands.) 


XXXII.— STRUCTURE  OF  A  TYPICAL  GLAND. 

Apparatus. — Microscope  and  accessories  used  in  the  study  of  tis- 
sues, prepared   slide  of  crypt  of  Lieb- 
erkiihn  from  the  small  intestine  of  man. 
(Any    other     gland    preparation    will    I 
serve.) 

Directions. — Examine  first  with 
the  low  power.  Draw  the  entire 
gland  and  note  the  following  points : 
the  kind  of  tissue,  the  arrangement 

Of    the    Cells,    the     gland    lumen,    Or    FIG.  25.— A    Salivary    Gland:  a, 
i  •  A  TTT-  j_i       J.T          T_  •    l~         lumen  of  a  gland  in  longitudi- 

central    cavity.      With   the    high     nal  section;  b>  a  gland  in  cross 
power  examine  a  few  of  the  cells     section'  c<  connective  tissue. 
and    their    contents.     Draw   and    note    the  position    of 


52 


EXPERIMENTAL   PHYSIOLOGY 


the  nucleus,  the  protoplasm,  and  the  secretion  in  various 
cells.  Fig.  26  illustrates  the  relation  of  the  simple,  tubular 
gland,  such  as  you  have  just  studied,  to  the  compound 

forms. 


FIG.  26. — Forms  bf  Glands. 


ORGANS  AND  PROCESSES  OF  DIGESTION 


XXXIII. — DISSECTION  OF  A  RAT'S  DIGESTIVE  ORGANS. 

Apparatus. — Chloroformed  rat,1  dissecting  tray  with  wax  lining, 
scissors,  forceps,  bristle  probes,  10%  alcohol  or  1%  formalin. 

Directions. — Lay  the  rat  on  its  back  in  the  tray,  stretch, 
and  tie  or  pin  the  legs  as  in  the  diagram.  Cover  with  10% 
alcohol  or  1%  formalin. 

Locate  the  lower  end  of 
the  breast  bone  and  slit  the 
skin  from  this  point  to  the 
anus.  On  each  side  at  the 
middle  point  of  the  slit, 
make  a  slit  at  right  angles. 
Turn  back  the  four  flaps 
and  pin  them. 

Note  the  thin  membrane 
(peritoneum)  lining  the  abdo- 
men. Is  it  flexible?  Remove 
this  and,  without  disturbing 
the  underlying  parts,  locate 

the  stomach,  the  liver,  and 

.,    T  .    .      .  FIG.  27. 

the  coiled  intestine. 

Press  the  intestine  downward  and  determine  the  size, 
position,  shape,  and  color  of  the  stomach.  Find  the  ends 


1  This  exercise  may  be  made  a  demonstration, 
animal  such  as  the  rabbit  would  be  preferable. 

53 


In   that  case  a  larger 


54  EXPERIMENTAL   PHYSIOLOGY 

that  are  connected  with  the  intestine  (pyloric  end)  and  with 
the  esophagus,  or  gullet  (cardiac  end).  Note  the  covering 
of  blood  vessels. 

In  the  fold  of  the  intestine  (duodenum)  next  to  the  stom- 
ach, locate  the  fatty-looking  pancreas.  Find  its  duct  and 
trace  its  connection  with  the  duodenum. 

Press  forward  the  liver  and,  on  its  posterior  surface,  find 
the  bile  sac.  Locate  the  connection  of  this  with  the  two 
lobes  of  the  liver  (the  hepatic  ducts).  Open  this  sac  and, 
with  the  probe,  find  its  connection  (the  bile  duct)  with  the 
pancreatic  duct  and  the  duodenum.  Note  that  the  bile  duct 
and  pancreatic  duct  fuse  and  enter  the  duodenum  by  a  com- 
mon duct. 

Examine  the  membrane  (mesentery)  which  supports  the 
intestine.  Note  its  blood  vessels.  Carefully  unravel  the  in- 
testine (Caution!  do  not  break  it)  from  the  stomach  to  the 
anus.  Determine  the  relative  lengths  of  the  small  and  the 
large  intestine  and  the  method  of  their  joining.  (This  con- 
nection is  guarded  by  a  valve*  which  acts  in  such  a  way  as 
to  prevent  matter  returning  from  the  large  to  the  small 
intestine.) 

Slit  the  stomach  just  below  the  gullet  entrance  and,  with 
the  probe,  find  its  connection  with  the  mouth.  Above 
the  liver  and  the  stomach,  find  the  muscular  partition 
(diaphragm)  separating  the  abdominal  from  the  thoracic 
cavity. 

Illustrate,  by  a  diagrammatic  drawing,  the  connections 
of  the  following  parts:  mouth,  gullet,  stomach,  liver,  pan- 
creas, small  intestine,  large  intestine. 

Carefully  remove  the  stomach,  liver,  pancreas,  and  intes- 
tines, and  preserve  the  rest  of  the  animal  for  further  dis- 
section in  85%  alcohol  or  4%  formalin. 


ORGANS   AND   PROCESSES   OF   DIGESTION  55 

XXXIV.— THE  TEETH. 

Apparatus. — A  hand  mirror,  a  molar  tooth  sawed  in  vertical  sec- 
tions, an  apple. 

Directions.— A.  Kinds  of   Teeth.    With  the  aid  of  the 

mirror  and  the  finger  count  the  number  of  teeth  on  each  jaw. 
Is  the  number  the  same?  Note  that  they  may  be  divided 
into  four  classes  according  to  shape.  How  many  broad 


a 


d 


FIG.  28. — a,  incisors;  6,  canines;  c,  premolars;  d,  molars. 

teeth  (incisors)  have  you  in  the  front  of  each  jaw?  How 
many  with  one  point  on  the  surface  (canines)!  How  many 
with  two  surface  points  (bicuspids  or  premolars)?  With 
more  than  two  surface  points  (molars)?  Tabulate  these 
numbers  as  follows: 


UPPER   JAW                                  LOWER  JAW 

Incisors 
Canines 
Premolars 
Molars 

Grand  Total 


56  EXPERIMENTAL   PHYSIOLOGY 

Examine  the  mouths  of  animals,  such  as  the  squirrel  or 
rat,  the  cat  or  dog,  and  the  horse  or  cow.  How  do  they 
differ  as  to  the  kind  and  number  of  their  teeth?  What  kind 
of  food  does  each  animal  eat?  Which  kind  of  food  requires 
the  most  chewing?  Do  you  see  any  connection  between 
the  food  and  the  kind  of  teeth  which  predominates  in 
animal? 

B.  Structure  of  a  Tooth.  Draw  J^tion  of  a  molar  tooth. 
Find  the  following  parts :  the  crown,  the  neck,  roots  or  fangs, 
the  covering  of  the  crown  (enamel),  the  covering  of  the  fangs 
(cement),  the  central  or  pulp  cavity  with  nerve  and  blood 
vessel  aperture,  the  middle  layer 
(dentine).  Label  all  these  parts  in 
your  drawing.  Examine,  if  possi- 
ble, the  jaw  of  a  human  skeleton  to 
show  the  insertion  of  the  teeth  in  it. 
C.  The  Use  of  the  Teeth.  Bite  off 
a  piece  of  apple  and  chew  it.  An- 
swer the  following  questions:  Which 
teeth  are  used  in  the  biting  off'  of 
the  apple?  Which  to  chew  it  into 
FIG.  29.— A  Moiar:  k,  crown;  small  pieces?  Why  are  ^these  latter 

*S'£S*£*  best  adaPted  to  breakup  the  food? 

cavity;  c,  cement.  Qf  what  advantage  is  it  that  a 

horse's  molars  are  ridged  on  the  surface?  Could  you  tell 
from  the  examination  of  the  teeth  the  kind  of  food  an  ani- 
mal eats? 

When  a  tooth  decays  what  part  actually  decays?  What 
is  the  difference  in  the  functions  of  the  enamel  and  of  the 
dentine?  How  does  the  location  of  the  nerves  in  the  pulp 
cavity  protect  them?  Why  is  a  decayed  tooth  apt  to 
ache? 


ORGANS   AND   PROCESSES   OF   DIGESTION  57 

XXXV.— PREPARATION  OF  DIGESTIVE  FLUIDS  (OPTIONAL). 

A.  Collection  of  Saliva.    Wash  the  mouth  out  thoroughly 
with  warm  water  to  remove  all  foreign  matter.     Bow  the 
head  forward,  turn  out  the  lower  lip,  and  collect  the  clear 
saliva  as  it  flows  over  the  center  of  the  lip.     Collection  should 
be  made  only  a  short  time  previous  to  use  in  experimenting. 
The  saliva  should  give  no  reaction  with  Fehling's  solution. 

B.  Artificial  Gastric  Juice.    Obtain  a  pig's  stomach.    Cut 
it  open  and  wash  its  contents  out  by  gently  flushing  it  with 
water.     Remove  the  mucous  membrane  from  the  cardiac 
end,  and  after  drying  this  with  filter  paper  mince  it  and  bottle 
with  four  or  five  ounces  of  glycerine.     (The  glycerine  dis- 
solves the  pepsin.)     After  three  days  filter  through  muslin. 
The    filtered   solution   may   be   kept  indefinitely.     When 
required    for   use    add   0.2%    hydrochloric  acid1    in    the 
ratio  of  one   part  of  the  acid  to  ten  parts  of  glycerine 
solution. 

A  substitute  for  the  above  is  solid  pepsin  powder  dis- 
solved in  water.  For  use,  this  should  be  treated  with 
0.2%  hydrochloric  in  the  same  way  as  the  glycerine  so- 
lution. , 

C.  Artificial  Pancreatic  Juice.     Soak  the  pancreas  of  a 
pig  in  water  over  night.     Then  remove  it  from  the  water, 
mince,  and  add  ten  times  its  volume  of  glycerine.     (Glyc- 
erine dissolves  the  pancreatin.)     Filter  as  with  gastric  juice. 
This  preparation  is  suited  to  the  digestion  of  starches  and 
proteids.     For  action  on  fats  add  ten  volumes  of  1.5%  solu- 
tion of  sodium  carbonate,  shake  well,  and  filter. 

A  substitute  for  the  glycerine  solution  may  be  made  by 

1  That  is,  dilute  hydrochloric  acid  containing  2  parts  of  the  concentrated 
commercial  acid  to  998  parts  of  water. 


58  EXPERIMENTAL   PHYSIOLOGY 

dissolving  the  solid  pancreatin  powder  in  water.  For  fats 
add  to  this  the  sodium  carbonate  solution  in  the  same  way 
as  to  the  glycerine  solution. 

D.  Bile.     Open  and  extract  the  contents  of  an  ox  gall 
or  dissolve  prepared  ox  gall  in  water. 

E.  Temperature  Conditions.    To  obtain  the  best  results  in 
all  artificial  digestion  experiments  keep  the  materials  used 
as  near  a  constant  temperature  as  is    possible.     For  this 
purpose  it  is  suggested  that  a  constant  temperature  water 
bath  be  used,  if  possible.     If  this  is  unavailable  an  ordinary 
drying  oven  may  be  used  with  an  Argand  burner.     Another 
substitute  is  a  double  boiler, — such  as  is  used  in  cookery, — 
with  the  Argand  burner.     Place  in  test  tubes  the  fluids  and 
materials  to  be  digested.     Cover  the  inner  chamber  of  the 
double  boiler  with  a  wooden  cover  having  holes  bored  to 
fit  the  test  tubes,  and  suspend  the  tubes  in  these.     Heat 
the  water  in    the  outer  part  to  the  temperature  desired 
and  adjust  the  Argand  burner  to  maintain  just  that  temper- 
ature. 


XXXVI. — DIGESTION  OF  THE  MOUTH — SALIVA. 

Apparatus. — A  little  salt,  dry  cracker,  dilute  starch  paste,  white 
of  egg,  olive  oil,  saliva,  litmus  paper,  Fehling's  solution,  concentrated 
hydrochloric  acid,  test  tubes,  constant  temperature  apparatus. 

Directions. — A.  General  Functions  of  Saliva.  Clear  the 
mouth  of  saliva  by  swallowing,  and  wipe  dry  the  top  of  the 
tongue.  Place  on  the  tongue  a  bit  of  salt.  Can  you  taste 
the  salt?  Close  the  mouth,  letting  the  salt  stay  on  the 
tongue.  What  happens  in  the  mouth?  Where  does  the 
saliva  come  from  in  the  mouth?  Where  is  it  made?  Was 
the  presence  of  the  salt  on  the  tongue  sufficient  to  cause  its 


ORGANS   AND   PROCESSES   OF   DIGESTION  59 

flow?  What  does  it  do  to  the  salt?  Can  you  taste  the  salt 
now?  Do  you  think  the  effect  would  be  the  same  if  the 
salt  had  been  dissolved  in  water?  Verify  by  placing  a 
drop  of  salt  water  on  the  dry  tongue.  Name  two  functions 
of  saliva  that  this  experiment  shows. 

Again  clear  the  mouth  of  saliva,  wipe  the  tongue  dry,  and 
place  on  it  some  powdered  cracker.  Try  to  swallow  the 
cracker.  Is  it  easily  done?  With  the  tongue  moisten  the 
cracker  with  saliva  and  try  to  swallow.  Is  swallowing  easy 
now?  What  is  another  function  of  saliva? 

Chew  some  of  the  cracker  slowly  and  note  if  any  change 
takes  place  in  its  taste.  Place  on  the  dry  tongue  some 
cracker  moistened  with  water.  Is  the  taste  the  same? 
What  power  has  the  saliva  that  is  not  due  to  its  liquid 
quality  only?  (This  last  power  of  the  saliva  is  called  its 
chemical  power  as  distinguished  from  its  purely  mechani- 
cal properties.) 

B.  Enzyme  Action  of  Saliva.  Place  in  four  test  tubes  a 
little  thin  starch  paste.  Add  a  cubic  centimeter  of  clear 
saliva  to  each,  and  label  Tubes  1,  2,  3,  4.  Add  a  few 
drops  of  concentrated  hydrochloric  acid  to  the  fourth 
tube.  In  a  fifth  tube  place  1  c.c.  of  saliva  and  a  little 
minced  white  of  egg,  and  label  Tube  5.  In  a  sixth  tube 
place  1  c.c.  of  saliva  and  a  few  drops  of  olive  oil.  Label 
Tube  6.  Shake  each  tube.  Pack  Tube  2  in  ice,  and  keep 
Tube  3  in  boiling  water. 

Tube  1.  Test  the  mixture  with  litmus  paper.  Is  it  acid 
or  alkaline?  Now  heat  gently  to  a  temperature  of  36°  C. 
Keep  at  this  temperature  for  twenty  minutes  and  then 
test  with  Fehling's  solution.  What  has  the  saliva  done 
to  the  starch?  See  Ex.  XXX.  What  caused  the  change 
in  the  taste  of  the  cracker  in  A? 


60  EXPERIMENTAL   PHYSIOLOGY 

Tube  2.  After  the  second  tube  has  been  in  ice  twenty 
minutes  test  with  Fehling's  solution.  What  is  the  effect 
of  cold  on  the  action  of  saliva? 

Tube  3.  Keep  the  third  tube  in  boiling  water  twenty 
minutes  and  test  as  above.  What  is  the  effect  of  high 
temperatures  on  the  action  of  saliva? 

Tube  4.  Heat  the  fourth  tube  to  36°C.  for  twenty  min- 
utes and  then  test  as  above.  Does  the  Fehling's  solution 
give  any  test  for  sugar?  (Acids  prevent  the  enzyme  ac- 
tion of  saliva.) 

Tube  5.  Heat  the  fifth  tube  to  36°  C.  for  twenty  minutes 
and  then  test  with  Fehling's  solution.  Does  saliva  convert 
white  of  egg  to  sugar?  (Saliva  does  not  affect  any 
proteid.) 

Tube  6.  Treat  Tube  6  in  the  same  way  as  Tube  5.  Does 
saliva  convert  olive  oil  to  sugar?  (Saliva  does  not  affect 
any  fats  and  oils.) 

(The  action  of  saliva  is  due  to  the  presence  of  an  en- 
zyme called  ptyalin,  which  converts  starch  to  grape 
sugar.) 

Tabulate  all  the  functions  of  saliva. 


XXXVII. — DIGESTION  OF  THE  STOMACH — GASTRIC  JUICE. 

Apparatus. — Glycerine  solution  of  pepsin  or  solid  pepsin  dis- 
solved in  water,  0.2%  hydrochloric  acid,  concentrated  hydrochloric 
acid,  caustic  soda,  alcohol,  minced  white  of  egg,  starch,  olive  oil, 
milk,  rennet  dissolved  in  water,  test  tubes,  dialyzer,  constant  tem- 
perature apparatus,  distilled  water,  materials  for  xanthoproteic  and 
biuret  tests. 

Directions. — A.  Action  of  the  Enzyme  Pepsin  and  Hy- 
drochloric Acid.  Label  seven  test  tubes  Tube  1,  Tube  2, 


ORGANS  AND   PROCESSES   OF   DIGESTION  61 

etc.,  and  prepare  them  as  follows:  In  the  first  place  5  c.c. 
of  the  glycerine  solution  or  dissolved  pepsin  and  dilute  with 
10  c.c.  of  water.  In  the  second  tube  put  15  c.c.  of  the 
0.2%  hydrochloric  acid.  In  the  third,  fourth,  and  fifth  tubes 
place  15  c.c.  of  glycerine  solution  which  has  been  diluted 
previously  with  ten  parts  of  0.2%  hydrochloric  acid  to  one  of 
glycerine  solution.  Prepare  the  sixth  tube  in  the  same  way 
as  the  third  and  then  add  5  c.c.  of  concentrated  hydrochloric 
acid.  Prepare  the  seventh  tube  in  the  same  way  as  the  third 
and  then  add  5  c.c.  of  caustic  soda  solution.  Add  to  each  of 
•the  seven  tubes  some  minced  white  of  egg,  and  shake.  Place 
Tubes  1,  2,  3,  6,  and  7  in  a  temperature  of  36°  C.  and  keep 
at  this  temperature  for  twenty-four  hours.  Place  Tube  4  in 
ice.  Keep  Tube  5  in  boiling  water. 

At  the  end  of  twenty-four  hours  examine  all  the  tubes. 
In  which  is  the  white  of  egg  dissolved?  What  nutrient  forms 
the  bulk  of  white  of  egg?  From  the  result  in  Tube  2,  does 
hydrochloric  acid  alone  dissolve  white  of  egg?  What  is  the 
effect  of  cold  on  the  action?  of  high  temperature?  Does  ex- 
cess of  hydrochloric  acid  help  or  hinder  action?  Why  is  a 
basic  substance  like  sodium  bicarbonate  given  in  case  of  sour 
stomach?  Does  pepsin  act  in  the  presence  of  a  strong  base 
like  caustic  soda?  (Pepsin  requires  for  its  action  a  slightly 
acid  medium,  such  as  is  found  in  the  stomach.)  Will  ptyalin 
act  in  an  acid  medium?  Can  it  convert  starch  to  sugar  in 
the  stomach? 

Now  place  the  contents  of  Tube  3,  containing  the  dis- 
solved proteid,  in  the  dialyzer,  and  put  distilled  water  in 
the  outer  jar.  After  twenty-four  hours  test  the  water 
in  the  outer  jar  by  the  xanthoproteic  and  biuret 
tests  for  proteid.  Does  the  proteid  solution  pass  through 
the  membrane?  Does  white  of  egg  dialyze?  (See  Ex. 


62  EXPERIMENTAL   PHYSIOLOGY 

XXIX.)  This  form  of  crystalloiclal  proteid  is  called 
peptone. 

Add  a  little  alcohol  to  some  of  the  peptone  solution  re- 
maining inside  the  dialyzer.  Filter  off  the  precipitate. 
Does  it  resemble  coagulated  albumin?  Add  water  to 
some.  Does  it  dissolve?  Does  coagulated  albumin  dis- 
solve? 

Prepare  two  tubes  in  the  same  way  as  Tube  3,  but  sub- 
stitute starch  paste  in  one,  and  olive  oil  in  the  other,  for 
the  white  of  egg.  Examine  after  twenty-four  hours.  Are 
they  dissolved? 

B.  Action  of  the  Enzyme  Rennin.  Add  a  little  of  the 
rennet  ferment  (which  contains  rennin)  dissolved  in  water, 
to  a  little  milk  in  a  test  tube.  What  happens  to  the  milk? 
Filter  off  the  precipitate.  Test  it  for  proteid.  (Rennin 
coagulates  the  proteid  in  milk.) 

Now  add  a  little  of  the  glycerine  solution  of  gastric  juice 
to  some  milk.  Does  the  action  resemble  that  of  the  rennin 
solution?  (Gastric  juice  contains  rennin.  Pepsin  will  not 
convert  milk  proteid  into  peptone  unless  the  milk  proteid  is 
previously  coagulated;  hence  the  necessity  of  the  rennin 
action.) 

XXXVIII. — DIGESTION   OF  THE   INTESTINE — PANCREATIN 
AND  BILE  (OPTIONAL). 

Apparatus. — Prepared  solution  of  pancreatin  (see  Ex.  XXXV), 
1.5%  sodium  carbonate  solution,  solution  of  ox  gall,  hydrochloric 
acid,  caustic  soda,  materials  for  food  tests,  constant  temperature 
apparatus. 

Directions.—  A.  Action  of  the  Proteid  Enzyme  of  Pan- 
creatin (Trypsin).  Prepare  five  tubes  as  follows:  Into  each 


ORGANS   AND    PROCESSES   OF   DIGESTION  63 

put  10  c.c.  of  solution  of  pancreatin,  and  some  minced  white 
of  egg.  Label  Tubes  1, 2,  3,  4,  and  5.  To  Tube  4  add  5  c.c. 
of  hydrochloric  acid  and  to  Tube  5  add  5  c.c.  of  caustic 
soda  solution.  Keep  Tubes  1,  4,  and  5  at  36°  C.,  Tube  2 
on  ice,  and  Tube  3  in  boiling  water  for  twenty-four 
hours. 

At  the  end  of  twenty-four  hours  examine  all  the  tubes  and 
note  in  which  the  proteid  is  dissolved.  What  is  the  effect 
of  cold  on  the  action?  of  high  temperatures?  of  excess  of 
acid?  of  excess  of  alkali?  Test  Tube  1  with  litmus.  What 
is  its  reaction? 

(Pancreatin  contains  an  enzyme  called  trypsin,  which, 
like  pepsin,  acts  on  proteid  and  converts  it  into  peptone.) 
From  the  above  experiments,  does  trypsin  require  an  acid 
medium?  (Pepsin  will  not  act  in  the  intestine  because  the 
contents  of  the  intestine  are  alkaline.) 

B.  Action  of  the  Starch  Enzyme  of  Pancreatin  (Amylopsiri) . 
Place  a  little  pancreatin  solution  in  three  test  tubes  and 
label  Tubes  1,  2,  and  3. 

Tube  1.  Test  with  Fehling's  solution.  Does  the  pan- 
creatin solution  contain  grape  sugar? 

Tubes  2  and  3.  Add  to  the  second  and  third  tubes  a  little 
dilute  starch  paste.  Test  with  litmus.  Is  the  solution  acid 
or  alkaline?  To  Tube  3  add  enough  hydrochloric  acid  to 
give  a  distinct  acid  reaction  with  litmus.  Keep  both  tubes 
at  36°  C.  for  twenty-four  hours.  Then  test  with  Fehling's 
solution.  Record  results.  Are  they  the  same  in  both 
tubes? 

(Amylopsin  will  act  only  in  a  basic  medium.) 

C.  Emulsion  and  Action  of  Fat  Enzyme  (Steapsin).    To 
pancreatin  solution  add  the  1.5%  sodium  carbonate  solu- 
tion as  directed  in  Ex.  XXXV,  C.     Shake  some  olive  oil  in 


64  EXPERIMENTAL   PHYSIOLOGY 

a  test  tube  with  this  solution.  Let  it  stand  a  moment. 
Do  the  oil  drops  reunite  after  separation  as  when  shaken 
with  water?  Is  the  oil  dissolved?  (This  is  an  emulsion, 
which  is  formed  when  separated  particles  of  oil  are  kept 
from  reuniting  by  some  surrounding  medium.  Such  action 
is  called  mechanical  as  contrasted  with  the  chemical  action 
of  a  ferment.) 

Boil  some  olive  oil  with  caustic  soda.  Smell  this  solu- 
tion and  describe  its  odor.  Taste  it.  What  has  been 
formed?  Is  this  product  soluble  in  water?  (The  conver- 
sion of  fat  into  soluble  soap  is  called  saponification.  This 
action  is  performed  by  the  pancreatin,  without  boiling,  by 
aid  of  the  contained  ferment  called  steapsin.) 

D.  Action  of  Bile.  Examine  some  of  the  gall  from  an  ox 
gall.  What  is  its  color?  taste?  (Human  gall,  or  bile,  is 
golden  brown.)  Test  some  of  this  ox  gall  with  litmus.  Is 
it  acid  or  alkaline?  Shake  up  some  of  the  gall  with  olive 
oil.  Does  it  emulsify  the  oil?  Add  some  of  the  gall  (bile) 
to  minced  white  of  egg  and  keep  at  36°  C.  for  twenty-four 
hours.  At  the  end  of  that  time  test  the  mixture  with  food 
tests.  Has  the  bile  converted  the  white  of  egg?  Repeat, 
using  starch  paste  instead  of  white  of  egg,  and  follow  with 
food  tests.  Has  the  bile  converted  the  starch?  (Bile  con- 
tains no  enzyme  and  hence  can  not  convert  any  form  of 
nutrient.) 

XXXIX. — DIGESTION  OF  MINERAL  SALTS  (OPTIONAL). 

Apparatus. — Phosphate  of  lime,  sodium  chloride  (common  salt)> 
dilute  hydrochloric  acid  (10%),  test  tubes,  evaporating  dish. 

Directions. — Shake  up  some  sodium  chloride  with  water 
in  a  test  tube.  Do  the  same  with  some  phosphate  of  lime 


ORGANS   AND    PROCESSES   OF   DIGESTION 


65 


in  another  tube.  Do  the  salts  dissolve?  Soluble  salts  may 
be  digested  in  all  parts  of  the  digestive  tube,  since  all  con- 
tain water.  Salts  which  are  insoluble  require  special  treat- 
ment. 

Place  some  phosphate  of  lime  in  the  10%  hydrochloric 
acid.  What  happens?  Is  this  solution?  To  determine  this 
point  pour  some  of  the  lime  and  acid  mixture  into  an  evap- 
orating dish  and  evaporate  to  dryness.  Does  the  residue 
taste  like  phosphate  of  lime?  Is  it  soluble  in  water?  Since 
the  hydrochloric  acid  is  used  up,  the  action  is  not  that  of 
an  enzyme.  The  resulting  residue  is  not  phosphate  of  lime; 
hence  the  action  is  not  a  simple  solution.  What  has  taken 
place  is  a  chemical  combination  of  hydrochloric  acid  and  the 
phosphate,  producing  a  salt  which  is  soluble  in  water.  This 
process  illustrates  a  method  of  converting  insoluble  salts  into 
forms  soluble  in  water,  and  is  a  process  that  takes  place  in 
the  stomach. 


XL. — TABULATION  OF  NUTRIENT  DIGESTION  (OPTIONAL). 

Directions. — Fill  out  the  following  table  from  the  results 
obtained  in  the  preceding  exercises.  If  a  given  nutrient 
is  digested  by  more  than  one  reagent,  indicate  by  separate 
entries  for  each  as  indicated  in  the  table. 


NUTRIENT. 

REGION  OF  ALIMENTARY 
TRACT  DIGESTED  IN. 

DIGESTIVE    REAGENT. 

NAME     OF     DIGESTED 
PRODUCT. 

Proteid 

Proteid 

Starch 

Starch 

Fats 

Fats 

Soluble  Salts 

Insol.  Salts 

66 


EXPERIMENTAL   PHYSIOLOGY 


XLI. — MICROSCOPIC  ANATOMY  OF  THE  DIGESTIVE  TRACT 

(OPTIONAL)  . 

Apparatus. — Prepared  slides  of  the  cross  sections  of  the  walls 
of  the  esophagus  (middle  part),  stomach  (pyloric  section),  small 
intestine  (injected  blood  vessels);  compound  microscope. 

Directions. — Make  drawings  of  each  section  studied  and 
label  the  parts.  See  Figs.  30  and  31. 


FIG.  30. — Vertical  Section 
of  the  Coats  of  the 
Stomach:  d,  surface  of 
mucous  membrane,  and 
mouths  of  gastric  folli- 
cles; m,  gastric  tubuli, 
or  follicles;  mm,  dense 
connective  tissue;  sm, 
sub-mucous  tissue;  cm, 
transverse  muscular  fi- 
bers; Im,  longitudinal 
muscular  fibers;  s,  fi- 
brous, or  serous,  coat. 


FIG.  31. — Section  of  Injected  Small  Intestine 
of  Cat:  a,  6,  mucosa;  g,  villi;  i,  their  absorb- 
ent vessels;  h,  simple  follicles;  c,  muscularis 
mucosse;  d,  sub-mucosa;  e,  e',  circular  and 
longitudinal  layers  of  muscle;  f,  fibrous  coat. 
All  the  dark  lines  represent  blood  vessels 
filled  with  an  injection  mass. 


BLOOD 

XLII. — GENERAL   PROPERTIES   OF   BLOOD. 

Apparatus. — Glass  slides  and  cover  glasses,  magnifier,  microscope, 
needle,  normal  salt  solution  (0.6%  solution),  neutral  carminate  of 
ammonia. 

Directions.— Wind  a  handkerchief  tightly  around  the 
thumb,  just  below  the  joint.  Now  bend  the  upper  joint. 
The  blood  will  collect  on  the  top  of  the  thumb  just  below 
the  nail.  Sterilize  a  needle  by  holding  it  a  second  in  a  flame, 
and  prick  the  thumb  just  below  the  nail.  The  blood  from 
the  puncture  may  be  easily  and  quickly  transferred  to  a 
glass  slide. 

A.  With  a  magnifier  examine  a  drop  mounted  as  above. 
Is  it  all  liquid?  Is  it  the  same  color  throughout?  Describe 
the  color  at  the  edge  of  the  drop.  Let  the  drop  remain  on 
the  slide  for  ten  minutes  and  examine  again.  Is  it  liquid 
now?  Prick  at  it  with  the  needle  point  and  describe  its 
consistency.  This  formation  is  called  a  clot.  Examine  the 
puncture  on  the  thumb  with  the  magnifier.  Has  it  stopped 
bleeding?  What  is  the  condition  of  the  blood  on  the  surface 
of  the  puncture?  Does  it  resemble  the  condition  of  the  drop 
on  the  slide?  Bind  up  the  thumb  as  before  and  flex  the 
upper  joint.  Does  the  puncture  bleed  again?  Wash  off 
the  clot  with  water.  Does  the  bleeding  begin  again  now? 
What  is  the  advantage  of  this  clotting  action  of  the  blood 

when  exposed  to  air? 

67 


68 


EXPERIMENTAL   PHYSIOLOGY 


B.  Mount  a  drop  of  blood  quickly,  and  examine  at  once 
with  the  high  power  of  the  microscope.  Note  the  rouleaux 
of  colored  corpuscles.  What  is  their  color?  Note  also  the 
white  or  colorless  corpuscles  (colorless  corpuscles  tend  to  stick 


FIG.  32. — Blood  Corpuscles:  A,  red  corpuscles  in  rouleaux;  a,  a,  colorless  corpuscles 
(X  400);  B,  red  corpuscles  in  focus;  C,  view  of  edge;  D,  three-quarters  view;  E, 
red  corpuscle  swollen  with  water;  F,  G,  H,  distorted  red  corpuscles. 

to  glass ;  hence  they  will  remain  if  the  cover  glass  is  pressed 
with  a  needle  so  that  the  current  will  drive  the  others  aside ; 
and  they  can  then  be  more  readily  seen) .  What  is  the  color 
of  the  liquid  in  which  the  corpuscles  are  floating?  This 
liquid  is  called  the  plasma.  Let  this  preparation  stand  for 
fifteen  minutes  and  then  run  under  the  cover  glass  a  drop 
of  strong  solution  of  neutral  carminate  of  ammonia.1  This 
decolorizes  the  red  corpuscles  but  brings  out  the  nuclei  of 
the  white  corpuscles  and  the  fibrin  filaments.  Draw  some 
of  the  white  corpuscles  and  note  the  shape  of  the  fibrin  fila- 
ments. Note  how  the  entanglement  of  these  filaments  forms 
the  foundation  of  the  clot. 

C.  Mount  a  drop  of  blood  as  in  B,  but  before  covering  it 
with  the  cover  glass,  add  a  drop  of  normal  salt  solution. 
This  causes  the  separation  of  the  red  corpuscles.  Draw  a 
surface  view  and  an  edge  view  of  a  red  corpuscle  under  the 

*A  permanent  mount  may  be  made  of  this  preparation  if  a  little  glycerine 
is  allowed  to  diffuse  under  the  cover  glass  and  the  cover  slip  is  then  cemented 
to  the  glass  with  gold  size. 


BLOOD  69 


high  power.     How  do  red  corpuscles  differ  in  appearance 
from  the  white  corpuscles?    Have  they  a  nucleus? 


XLIII. — STUDY  OF  BEEF  OR  PIG  BLOOD. 

Apparatus.— Five-ounce  bottles,  fresh  blood,  egg  beater,  test 
tubes,  food-testing  materials,  constant  temperature  apparatus,  com- 
pound microscope,  slides  and  cover  glasses,  distilled  water,  dialyzer. 

Directions. — A  quart  or  more  of  fresh-drawn  blood 
should  first  be  obtained  from  a  butcher.  Divide  this  among 
the  five-ounce  bottles  as  follows : 

Bottle  1.  Fill  with  fresh  blood  and  cork  so  as  to  exclude 
all  air. 

Bottle  2.     Fill  two- thirds  full  and  leave  uncorked. 

Bottles  3,  4,  and  5.     Fill  two-thirds  full  and  cork. 

Place  the  remainder  of  the  blood  in  a  basin  and  whip 
vigorously  with  an  egg-beater  or  twigs.  Take  off  the  stringy 
substance  that  collects  on  the  beater,  and  wash  it  in  water 
until  it  has  lost  its  red  color.  Put  it  in  Bottle  6  and  add 
to  it  a  little  water. 

Pour  the  whipped  blood  into  a  suitable-sized  bottle  and 
label  it  Bottle  7.  Leave  uncorked. 

A.  Study  of  Coagulation  or  Clotting.  Place  Bottles  1  and 
2  in  ordinary  room  temperature.  Examine  frequently  for 
several  days.  In  which  bottle  does  the  clot  form  quickest? 
Does  the  absence  of  air  in  Bottle  1  have  any  effect  on  the 
rate  of  clotting? 

Place  Bottle  3  in  a  constant  temperature  of  36°  C.  and 
pack  Bottle  4  in  ice.  In  which  does  the  clot  form  quickest? 
Does  temperature  affect  the  rate  of  clotting? 

Place  Bottle  5  under  the  same  conditions  as  1  and  2  but 


70  EXPERIMENTAL   PHYSIOLOGY 

shake  from  time  to  time.  Does  this  affect  the  rate  of 
clotting? 

Place  Bottle  7  with  1, 2,  and  5.  Examine  after  three  days. 
Has  this  blood  clotted?  What  is  missing  in  it?  (The  sub- 
stance is  called  fibrin.) 

Summarize  -the  conditions  best  suited  to  clotting.  The 
exact  reason  why  blood  clots  when  it  is  not  in  a  healthy 
blood  vessel  is  unknown. 

B.  Study  of  the  Clot.     Pour  off  the  liquid  from  all  the 
bottles  in  which  a  clot  has  formed  and  place  it  in  Bottle  8. 
(This  liquid  is  called  serum.)    Then  break  one  of  the  bottles 
containing  a  clot  and  remove  the  clot  entire.     What  is  its 
shape?  color?  consistency?    Cut  off  a  thin  slice  of  it  and 
examine  it  under  the  microscope.     What  parts  can  you 
distinguish?    Does  it  contain  any  corpuscles?    The  jelly- 
like  substance  is  to  be  found  in  its  pure  state  in  Bottle  6. 
Examine  some  of  this  fibrin.     What  is  its  color?    Test  it 
for  proteid.     What  is  the  result?    Explain  in  a  few  words 
the  formation  of  a  clot  and  the* part  played  in  its  formation 
by  the  fibrin  and  the  corpuscles. 

C.  Study  of  tJie  Serum.     Examine  the  liquid  in  Bottle  8. 
What  is  its  color?    Why  is  it  not  red? 

Test  a  little  with  iodine  solution  for  starch.  Since  starch 
must  be  digested  before  it  can  be  absorbed  into  blood,  why 
should  you  expect  this  result? 

Test  some  of  the  serum  with  Fehling's  solution  for  the 
presence  of  grape  sugar.  Do  you  get  a  strong  test?  What 
does  this  result  suggest  as  to  the  amount  present? 

Burn  a  little  serum  on  a  piece  of  platinum  foil.  Does  it 
contain  any  mineral  matter? 

Place  a  drop  on  a  piece  of  unglazed  paper  and  let  it 
evaporate.  Does  it  leave  a  grease  spot? 


BLOOD  71 

Heat  a  little  serum  and  test  for  proteid.  Can  the  proteid 
present  be  fibrin?  Reasons?  What  use  is  made  of  the 
foods  present  in  serum?  How  do  they  get  into  the  serum? 
(See  Ex.  XXX.)  What  is  one  function  of  the  blood? 

D.  Study  of  Defibrinated  Blood.  Examine  the  contents 
of  Bottle  7.  How  does  this  blood  differ  from  fresh  blood? 
from  serum? 

Place  some  of  this  blood  in  the  dialyzer.  Fill  the  outer 
jar  with  distilled  water.  Does  the  color  of  the  water  in  the 
outer  jar  change?  After  a  time  test  the  water  in  the  outer 
jar  for  proteid,  grape  sugar,  minerals.  What  part  of  the 
blood  dialyzes? 

Fill  a  bottle  half  full  of  defibrinated  blood  and  shake  it 
vigorously.  Does  it  change  in  color?  What  was  mixed 
with  the  blood  by  shaking  the  bottle?  (One  function  of  the 
colored  corpuscles  is  to  take  up  oxygen.  This  function, 
which  heightens  their  color,  is  due  to  the  iron  they  contain; 
see  Ex.  VI.)  Look  up  in  your  text  the  use  of  the  white 
corpuscles. 


CIRCULATION  AND  THE  BLOOD  SYSTEM 

XLIV. — PROPERTIES    AND    LOCATION    OF    ARTERIES    AND 

VEINS. 

Apparatus. — A  watch  with  a  second  hand,  a  needle,  a  chemical 
thermometer. 

Directions. — Examine  the  back  of  the  hand  and  wrist 
and  locate  the  dark-colored  veins.  Is  the  blood  this  color? 
Place  your  finger  on  a  vein.  Can  you  feel  any  motion?  Is 
there  any  difference  in  the  size  and  prominence  of  the  veins 
when  you  exercise  violently?  Why  should  you  expect  this 
result? 

Find  your  pulse  on  the  palm  side  of  the  wrist.  Count  its 
beats  and  record  the  number  per  minute.  Test  this  rate  at 
various  times  of  the  day.  Is  it  uniform  at  all  times?  Test 
your  body  temperature  at  the  same  time  by  placing  the  bulb 
of  the  chemical  thermometer  under  the  tongue.  Does  the 
temperature  vary  with  the  pulse  rate?  Does  either  increase 
after  violent  exercise?  If  food  is  burned  up  by  exercise,  and 
blood  contains  oxygen  and  food,  how  do  you  account  for 
these  effects? 

Examine  other  parts  of  the  body  for  veins  and  arteries 
(pulse  always  indicates  the  presence  of  an  artery).  Which 
are  most  numerous  on  the  surface?  Which  are  best  pro- 
tected? The  bleeding  of  a  cut  artery  is  much  more  difficult 
to  stop  than  that  of  a  vein,  owing  to  its  pulsation. 

72 


CIRCULATION   AND    THE   BLOOD   SYSTEM  73 

Examine  the  skin  on  the  back  of  the  hand  between  two 
veins.  Can  you  see  any  blood  vessels?  Place  the  finger 
on  this  part.  Can  you  feel  any  pulse?  Prick  through  the 
skin  at  this  point  with  a  sterilized  needle.  Does  the  punc- 
ture bleed  by  spurts  or  steadily?  The  small  blood  vessels 
filling  these  places  are  called  capillaries  on  account  of  their 
small  size  (capillus=a,  hair).  They  connect  the  veins  and 
arteries. 


XLV. — CIRCULATION  IN  A  FROG'S  FOOT. 

Apparatus. — Compound  microscope,  cover  slip,  live  frog,  shingle, 
wet  absorbent  cotton,  and  cloth. 

Directions. — Bind  a  live  frog  in  wet  absorbent  cotton, 
leaving  one  leg  extended.  Fasten  the  frog,  so  bound  in  place, 
on  a  frog  board  (a  piece  of  shingle  with  a  hole  the  size  of  a 
cover  slip  at  one  end).  Stretch  the  web  of  the  foot  over  the 
hole  in  the  board.  Fasten  it  securely,  with  the  stretched 
web  as  level  as  possible.  Mount  this  board  on  the  micro- 
scope stage  in  such  a  way  as  to  bring  the  web-covered  hole 
under  the  objective  of  the  microscope.  With  a  pipette 
place  a  drop  of  water  on  the  top  of  the  web,  and  cover  with 
a  piece  of  cover  slip.  Illuminate  in  the  usual  way  and  focus 
first  with  the  low  and  then  with  the  high  power. 

Note  the  network  of  blood  vessels  and  the  slow-moving 
stream  of  corpuscles  within  them.  Are  the  corpuscles  the 
same  size  and  shape  as  those  in  the  human  blood?  Is  there 
more  than  one  kind?  Observe  that  in  some  of  the  blood 
vessels  the  blood  moves  in  spurts  at  regular  intervals.  What 
kind  of  vessels  are  these?  Does  the  blood  in  these  flow  from 
or  toward  the  body?  Follow  the  course  of  the  blood  from' 
these  into  the  smaller  tubes  where  the  corpuscles  move  in 


74 


EXPERIMENTAL   PHYSIOLOGY 


almost  single  file.    Do  these  show  pulsations?    Trace  the  flow 
from  these  into  larger  vessels  where  no  pulsation  is  evident. 


FIG.  33. — Capillary  Circulation  in  the  Web  of  a  Frog's  Foot,  X  100:  °,  &.  small  veins, 
d,  capillaries  in  which  the  corpuscles  are  seen  to  follow  one  another  in  single  series; 
c,  pigment  cells  in  the  skin. 

Note  the  direction  of  flow  in  these  tubes.  What  is  the  name 
of  these  tubes?  Define  artery,  vein,  and  capillary  in  terms 
of  the  direction  of  blood  flow. 


XL VI. — MINUTE    STRUCTURE    OF    ARTERIES    AND    VEINS 

(OPTIONAL). 

Apparatus. — Prepared  slides  of    cross  sections  of  arteries  and 
veins,  compound  microscope. 

Directions.     Note  that  both  artery  and  vein  have  three 
coats:  a  lining  of  epithelial  cells  called  here  endothelium,  a 


CIRCULATION   AND   THE   BLOOD   SYSTEM  75 

middle  layer  consisting  of  a  mixture  of  muscle  and  elastic 
fibers,  and  the  outside  layer  or  coat  of  connective  tissue 
bundles.  Make  careful 
drawings  of  the  two  prep- 
arations, showing  the  lo- 
cation and  form  of  these 
layers,  and  label  the  above- 
mentioned  parts.  In  which 
of  the  two  forms  of  blood 
vessels  is  the  elastic  and 
muscular  coat  thickest? 
Why  should  you  expect 
this  condition  from  the 

method     Of    flow     Of     blood    Fl°-    34.— Cross   Section  of  an   Artery:    a, 
,  Tiru  *  l,  endothelium;    6,   muscular    layer;    c,  con- 

in     each:         What      IS      the        nective  tissue;  d,  small  artery  to  nourish 

special   advantage   of    the     lar*eone- 

elastic  fibers  in  the  artery?  In  what  way  do  they  aid  to 
keep  the  capillaries  filled  at  the  end  of  an  artery  pulsa- 
tion? Is  the  pressure  greatest  in  arteries  or  in  veins? 


XL VII. — STRUCTURE   OF  THE   HEART. 

Apparatus. — Sheep's  heart  from  the  butcher  with  pericardium 
attached,  bristle  seekers,  dissecting  instruments. 

Directions. — Locate  the  parts  named  below,  and  make 
drawings  to  show  their  position. 

A.  Note  that  the  heart  moves  easily  inside  a  loose  sac. 
Cut  this  pericardium  open  and  observe  its  slippery  inner 
coat.  Note  a  similar  coat  on  the  outside  of  the  heart. 
What  lies  between  these  two  coats?  This  liquid  and  the 
slippery  coats  prevent  friction  when  the  heart  pulses. 


EXPERIMENTAL   PHYSIOLOGY 


B.  Carefully  cut  away  the  pericardium  from  the  blood 
vessels,  and  the  fat  from  the  surface  of  the  heart.     Locate 


i 


FIG.  35. — Heart  in  position  with  pericardium  removed  (Human):  Tr,  trachea; 
L,  lungs;  RA,  LA,  right  and  left  auricles;  RV,  LV,  right  and  left  ventricles;  Ao, 
aorta  (two  branches);  SVC,  IVC,  superior  and  inferior  venae  cavse;  PA,  pulmonary 
artery. 

the  aorta,  vence  cavce,  pulmonary  veins  and  artery;  and  push 

bristle  seekers  through  these  blood  vessels  into  the  heart. 

C.  Examine  the  outside  of  the  heart  and  locate  the  follow- 


CIRCULATION   AND   THE   BLOOD   SYSTEM  77 

ing  parts  of  the  heart  proper:  right  and  left  auricks,  right  and 
left  ventricles.  By  right  and  left. are  meant  the  parts  of  the 
heart  that  are  right  and  left  in  its  position  in  the  body. 
Which  parts  have  the  thickest  walls?  The  waUs  are  made 
cf  muscle,  and  these  thick-walled  parts  do  the  pumping. 


FIG.  36.— Right  Auricle  and  Ventricle  (Sheep):  RA,  RV,  right  auricle  and  ven^ 
tricle;  IVC,  SVC,  inferior  and  superior  venae  cavse;  a,  b,  bristle  seekers  showing 
connections  between  auricle  and  ventricle,  auricle  and  vena  cava;  PA,  pulmonary 
artery;  tv,  tricuspid  valve;  pp,  papillary  muscle;  sv,  semilunar  valves. 

D.  Cut  off  carefully  the  front  walls  of  the  right  auricle 
and  ventricle.  By  means  of  the  bristles  locate  the  entrance 
into  the  auricle  of  the  inferior  and  superior  vence  cavce,  and 
the  entrance  into  the  ventricle  of  the  pulmonary  artery. 
Find  the  connection  between  the  auricle  and  the  ventricle 
and  note  the  tricuspid  valve  that  closes  this  entrance,  Lo- 


78 


EXPERIMENTAL   PHYSIOLOGY 


cate  also  the  chordce  tendince  that  attach  this  valve  to  the  pap- 
illary muscles  on  the  surface  of  the  heart.  What  is  the  effect 
of  the  contraction  of  the  ventricle  on  the  action  of  this  valve? 


Ao 


FIG.  37. — Left  Auricle  and  Ventricle  (Sheep):  a,  b,  c,  bristle  seekers  showing  con- 
nections of  auricle  with  ventricle,  of  auricle  with  veins,  and  of  ventricle  with  arter- 
ies; PV,  pulmonary  veins;  pp,  papillary  muscles;  mv,  mitral  valve;  PA,  pulmonary 
artery;  Ao,  aorta;  SVC,  superior  vena  cava. 

Note  finally  the  semilunar  valves  at  the  entrance  to  the  pul- 
monary artery.  How  does  their  arrangement  prevent  the 
backward  flow  of  blood  into  the  heart? 

E.  Cut  off  the  front  walls  of  the  left  auricle  and  ventricle 
in  the  same  way,    Have  they  any  connection  with  the  right 


CIRCULATION   AND   THE   BLOOD   SYSTEM  79 

side  of  the  heart?  Locate,  with  the  aid  of  the  bristles,  the 
entrance  of  the  pulmonary  veins.  How  many  enter  the 
auricle?  Find  the  entrance  from  the  auricle  to  the  ventricle, 
and  the  mitral  valve  which  guards  this  entrance.  Does  it 
show  chordae  tendinse  and  papillary  muscle  attachments? 
How  does  it  differ  in  shape  from  the  tricuspid?  Locate  the 
semilunar  valves  at  the  entrance  of  the  aorta. 

Make  a  careful  diagram  of  the  course  of  circulation  through 
the  heart  to  the  lungs  and  back  to  the  heart  and  body. 


THE    BODY   SKELETON 


81 


does  it  feel?    Heat  some  in  water  in  a  tube.    What  collects 
on  the  top  of  the  water? 

B.  The  Thigh   Bone,  or  Shank,  a  long 
bone.     Draw  the   bone,  and    shade  with 
different  colors  the  parts  that  are  covered 
with  cartilage  and  with  periosteum.    What 
is  the  function  of  the  enlarged  heads  of 
this  bone?     Of  what  advantage  is  it  that 
they  are  irregular  in  surface? 

Saw  the  bone  lengthwise,  draw,  and 
label  the  parts.  In  what  portion  of  the 
bone  is  the  marrow  most  plentiful?  Is 
the  shaft  solid?  What  is  the  advantage 
of  this  condition? 

C.  The  Dorsal  Vertebra.    Draw  a  dor- 
sal vertebra  from  the  side  and  from  the 
top.     With  the  aid  of  the  diagram  locate 
the  following    parts:    The  body   of    the 
vertebra,  spinous  process,  transverse  proc- 
esses,    spinal    cavity,     rib    articulations, 


FIG.  38.—  Thigh  Bone, 
in  Longitudinal  Sec- 
tion. 


FIG.  39.—  A  Dorsal  Vertebra:  1,  centrum  or  body;  2, 
spinous  process;  3,  spinal  cavity;  4,  transverse  process; 
5,  rib  articulation;  6,  vertebral  articulation. 


vertebral    articulations.     How   are    the    articulations  pro- 
tected?   What  is  the  function  of  the  processes? 


82  EXPERIMENTAL   PHYSIOLOGY 

L. — COMPOSITION  OF'BONE  (OPTIONAL). 

Apparatus. — Two  clean  ribs,  a  soup  bone  split  in  two,  20% 
hydrochloric  acid,  bottle  big  enough  to  hold  rib,  evaporating  dish, 
food-testing  materials,  Bunsen  burner. 

Directions.— A.  Place  one  of  the  ribs  in  the  bottle  and 
fill  the  bottle  with  the  20%  hydrochloric  acid.  Let  it  stand 
for  a  few  days.  At  the  end  of  that  time  examine  it.  Has  it 
changed  in  shape?  Take  it  out  of  the  bottle  and  bend  it. 
What  power  has  it  lost?  What  substance  is  left?  Hold  a 
little  of  it  in  the  flame.  Does  it  burn?  Pour  a  little  of  the 
acid  from  the  bottle  into  the  evaporating  dish  and  evaporate 
to  dryness.  What  kind  of  substance  is  left?  What  material 
did  the  acid  dissolve  out  of  the  bone? 

B.  Burn  the  other  rib.     What  is  the  shape  of  the  part  that 
is  left?    Is  it  flexible?    Put  some  of  it  in  the  acid.     Does  it 
dissolve?    Name  the  two  main  constituents  of  bone. 

C.  Cover  the  split  soup  bone  with  water  and  gradually 
bring  to  a  boil.     Strain  off  the.  liquid  and  let  it  cool.     What 
do  you  find  floating  on  the  surface?    What  forms  as  it  cools? 
What  is  the  character  of  this  substance?    Test  for  foods. 


LI. — STRUCTURE  OF  A  JOINT. 

Apparatus. — Fresh  leg  joint  of  lamb  or  veal,  scalpel. 

Directions. — Examine  the  tissue  that  binds  the  two 
bones  together.  What  is  the  character  of  these  bands,  or 
ligaments?  Are  they  flexible?  How  do  they  control  the 
direction  of  movement  of  the  bones?  Cut  off  the  ligaments 
with  a  scalpel.  Note  the  liquid  found  within.  What  does 
it  look  like?  (It  is  a  lubricant  called  synovial  fluid}. 


THE    BODY   SKELETON 


83 


Examine  the  ends  of  the  bones.  With  what  are  they 
covered?  Press  this  surface.  Is  it  elastic?  What  is  the 
advantage  of  this?  Is  the  surface  smooth?  Of  what  ad- 


Pelvic  Bone 

Synovial  Membrane 


-  -  Head  of  Femur 
---Round  Ligament 

Capsular  Ligament 


FIG.  40. — A   Joint. 


vantage  is  this?    What  is  the  reason  for  the  enlarged  ends  of 
the  bones?  for  their  irregular  surfaces? 


LIT. — FORMS  OF  JOINTS. 

Apparatus. — The  human  skeleton. 

Directions. — Examine  the  following  joints  and  describe 
the  range  of  motion  of  each:  Knee,  elbow,  vertebral, 
shoulder,  hip,  jaw,  head  and  spine,  bones  of  the  skull,  ribs. 

Name  the  bones  united  in  each  case  and  classify  the  joints 
under  the  following  names :  Hinge,  ball  and  socket,  gliding, 
rotary,  dovetail,  symphysis. 

Which  of  the  above  are  movable  joints?    fixed? 


MUSCLES  AND  MOTION 

LIU. — DISSECTION  OF  THE  MUSCLES. 

Apparatus. — The  body  of  the  rat  used  in  Ex.  XXXIII  (any 
other  animal  will  serve  the  purpose  and  if  a  demonstration  is  desired 
for  the  study  of  the  leg  muscles  the  leg  of  a  sheep  may  be  substi- 
tuted), scalpel. 

Directions. — Carefully  cut  off  the  hind  leg  of  the  rat, 
close  to  the  hip  joint,  and  remove  the  skin.  Note  the 
muscles  covering  the  bones  and  the  glistening  white  muscle 
sheath  (perimysiwn)  covering  each  muscle.  At  the  ends 
of  the  muscles  note  the  white  tendons.  Are  the  muscles 
attached  directly  to  the  bones?  The  end  of  the  muscle  that 
moves  most  in  contraction  is>  called  its  insertion;  the  one 
that  moves  least,  its  origin.  Where  are  the  tendons  most 
numerous?  How  does  this  arrangement  avoid  clumsiness 
in  the  foot?  Compare  with  the  arrangement  in  your  own 
hand  and  foot.  Is  it  the  same? 

Separate  the  tendons  and  muscles  without  cutting  them, 
and  pull  on  each  to  determine  'what  part  of  the  leg  it  con- 
trols. Muscles  that  extend  a  joint  are  called  extensors, 
those  that  bend  it  are  called  flexors.  Note  that  all  these 
muscles  have  a  thick  center,  or  belly,  and  tapering  ends  with 
tendons  attached  at  the  ends.  Those  muscles  with  two  ten- 
dons at  the  origin  are  called  biceps;  those  with  three,  triceps. 

Examine  one  of  these  tendons.     How  is  it  different  from  a 

84 


MUSCLES   AND   MOTION  85 

muscle?  Is  it  elastic?  Why  should  you  expect  this  from  its 
use? 

Remove  the  skin  from  the  sides  of  the  body.  How  do 
the  underlying  muscles  differ  from  the  leg  muscles?  Have 
they  tendinous  ends?  What  two  classes  of  muscles  based 
upon  their  form  can  you  name  from  your  study?  Mention 
some  other  parts  of  the  body  where  these  kinds  of  muscles 
can  be  found. 

Preserve  the  rest  of  the  rat's  body  for  future  use. 


LIV. — GROSS  STRUCTURE  OF  MUSCLE. 

Apparatus. — A  bellied  muscle  from  the  rat  or  frog  (a  piece  of 
fresh  beef  will  serve),  needles,  compound  microscope  and  slides,  food- 
testing  materials. 

Directions. — Boil  the  muscle  in  water  for  a  few  moments 
and  pick  it  to  pieces  with  the  needles.  Note  that  it  sepa- 
rates easily  into  bundles.  Why  is  cooked  beef  more  easily 
chewed  than  raw?  Examine  the  perimysium  covering  the 
bundles.  What  sort  of  tissue  is  it?  Describe  its  appear- 
ance. What  purpose  does  it  serve?  Place  one  of  these 
bundles  in  a  drop  of  water  on  a  slide  and  with  the  needles 
tear  off  the  perimysium  and  tease  the  bundle  into  fibers. 
Examine  one  of  these  fibers  under  the  low  power  of  the 
microscope.  Note  its  covering  (sarcolemma)  and  its  striated 
appearance.  All  muscles  under  direct  nerve  control  (vol- 
untary muscles)  show  this  striation.  (For  the  minute 
anatomy  of  this  fiber  see  Ex.  XXVII.) 

Apply  the  xanthoproteic  and  other  food  tests  to  pieces  of 
the  muscle.  From  the  strength  of  the  various  reactions, 
what  is  the  main  constituent  of  muscle?  Why  does  an 
athlete  require  a  diet  rich  in  proteid  ? 


86 


EXPERIMENTAL   PHYSIOLOGY 


LV. — NERVE  MUSCLE  PREPARATION  (OPTIONAL). 

Apparatus* — Put  a  frog  in  a  bottle  or  jar,  pour  in  a  little  chloro- 
form, and  cork  the  bottle.  As  soon  as  the  frog  is  still,  remove  it 
from  the  jar  and,  with  a  scalpel,  sever  the  spinal  cord  just  back  of 
the  skull.  With  a  wire,  destroy  the  brain  and  spinal  cord.  Dissect 


FIG.  41. — sc,  sciatic  nerve;  g,  gastrocnemius;  ad,  6,  etc.,  other  muscles. 


away  a  hind  leg;  remove  all  the  muscles  except  the  gastrocnemius, 
and  separate  this  at  its  lower  attachment.  Fasten  the  femur  strongly 
in  a  clamp.  With  a  pointed  glass  rod  separate  the  sciatic  nerve  at 
the  upper  part;  do  not  touch  it  with  metal  instruments.  Into  the 
lower  end  of  the  muscle  insert  a  hook  and  connect  it  with  a  lever 
as  in  Fig.  42.  Connect  a  copper  wire,  insulated  except  at  the  end 
which  is  to  be  used  as  an  electrode,  with  each  pole  of  a  battery  of 
two  dry  cells.  For  convenience  a  key  of  some  kind  may  be  inserted 
in  the  circuit  to  make  and  break. 


MUSCLES   AND   MOTION 


87 


Directions.— Touch  the  free  end  of  the  nerve  with  the 
two  electrodes.  What  happens  to  the  muscle?  Record  the 
extent  of  the  action. 
This  shows  that  nerve 
stimulation  may  cause 
the  muscle  to  move. 
Keeping  the  electrodes 
in  contact  with  the  nerve, 
note  whether  the  action 
continues.  Remove  the 
electrodes.  What  hap- 
pens? Repeat  this  proc- 
ess Several  times  and  FlG-  42.— Nerve  Muscle  Preparation:  s,  set 
,  ,  screw;  c,  clamp;  /,  femur;  m,  gastrocnemius; 

mark     the     distance     that        n,  sciatic   nerve;    h,  hook;    Z,  lever;    e,  elec- 

the    lever     moves    each      trodes;  b' battery- 
time.     Is   it  the   same?    Does  the   action  increase  or  de- 
crease?   This  result  illustrates  what  may  happen  from  over- 
stimulation;  namely,  muscle  fatigue. 

Repeat  the  experiment,  applying  the  current  to  the  body 
of  the  muscle  instead  of  the  nerve.  Compare  with  the  re- 
sults of  the  first  experiment  as  to  extent  and  strength  of  the 
action. 

In  both  of  the  above  experiments  what  property  of  the 
muscle  is  stimulated?  Why  is  muscle  called  contractile 
tissue? 


LVI. — STUDY  OF  LEVER  ACTION  (OPTIONAL). 

Apparatus. — Wooden  bar  with  holes  near  the  ends  and  at  the  mid- 
dle (exactly  halfway  between  the  end  holes),  spring  balances. 

Directions. — A.  Support  the  bar  by  the  middle  hole  (see 
Fig.  43,  A),  and  trim  the  bar  till  it  balances  level.     Fasten 


88, 


EXPERIMENTAL   PHYSIOLOGY 


the  spring  balances  in  the  two  end  holes.  Pull  down  on 
each,  keeping  the  bar  horizontal.  Compare  the  pulls  regis- 
tered by  the  balances.  What  is  their  relation?  Attach  one 
balance  halfway  between  the  end  and  middle  holes,  keeping 
the  second  balance  in  the  other  end  hole.  Pull  until  the  bar 


A.  B.  c. 

FIG.  43.— Forms  of  Levers:    A,   1st  class;   B,  2d   class;   C,  3d  class;  W,  weight;  F, 
fulcrum  or  pivot;  P,  pull. 

is  level  as  before.  What  is  the  relation  of  the  registered 
pulls  now?  Verify  the  following  law  by  changing  the  posi- 
tion of  the  two  balances. 

Weight  X  perpendicular  distance  from  the  pivot  equals 
Pull  X  perpendicular  distance  from  the  pivot.  (Perpendic- 
ular distance  is  measured  from  the  pivot  at  right  angles  to 
the  direction  in  which  the  force  is  acting.) 

This  arrangement  of  lever  is  called  a  lever  of  the  first  class. 

B.  Support  the  bar  by  one  end  hole,  and  at  the  extreme 
end  attach  a  weight  so  that  the  bar  will  balance  level ;  then 
insert  the  balances  in  the  other  two  holes  (see  Fig.  43,  B). 
Pull  down  with  the  one  nearest  the  pivot  (Weight),  and  up 
with  the  one  at  the  end  (Pull).     Record  the  pull  and  weight 
when  the  bar  is  level,  measure  the  distances  from  the  pivot, 
and  see  if  the  law  of  A  still  holds.    This  arrangement  is 
called  a  lever  of  the  second  class. 

C.  If  the  pull  nearest  the  pivot  be  called  the  Pull  and  the 


MUSCLES   AND   MOTION  89 

other  the  Weight,  the  arrangement  is  called  a  lever  of  the 
third  class  (see  Fig.  43,  C). 


LVIL — LEVERS  OF  THE  BODY  (OPTIONAL). 

Directions. — A.  Locate  on  the  upper  arm  the  biceps 
muscle,  or  flexor  of  the  arm.  Where  is  it  attached  to  the 
forearm  and  how  far  (perpendicular  distance)  from  the 
elbow?  Measure  the  perpendicular  distance  from  the  elbow 
to  the  center  of  the  palm.  If  now  we  put  a  weight  of 
ten  pounds  in  the  palm  and  bend  the  arm,  what  class  of 
levers  is  illustrated?  How  much  force  is  required  on  the 
part  of  the  muscle  to  raise  ten  pounds'  weight?  By  se- 
lecting different  weights  to  lift,  determine  the  maximum 
strength  of  the  biceps  muscle.  What  muscle  is  used  in 
striking  an  outward  blow  with  the  fist?  Where  is  it  located 
and  inserted?  Note  that  the  flexors  and  extensors  in  other 
parts  of  the  body  are  usually  arranged  in  pairs. 

B.  Examine  the  relation  of  the  muscle,  weight,  and  pivot 
in  the  following  cases,  and  tell  which  class  of  lever  each 
illustrates :  Jaw  action  in  chewing,  flexing  of  the  fingers, 
movement  of  the  legs  in  kicking,  bending  the  body,  move- 
ment of  the  foot  about  the  ankle  (see  Fig.  43). 

NOTE.— The  instructor  can  suggest  other  problems  of  the  above 
nature  to  make  clear  the  laws  of  lever  action. 


RESPIRATION 

LVIII. — DISSECTION  OF  A  RAT'S  LUNGS. 

Apparatus. — Body  of  t-he  rat  used  in  Exs.  XXXIII  and  LIII, 
scalpel,  glass  tube  of  one-eighth  inch  diameter. 

Directions. — Remove  the  skin  from  the  surface  of  the 
ribs  and  throat.  Examine  carefully  the  muscles  between 
the  ribs  (intercostals) .  Seize  the  base  of  the  breast  bone  and 
move  it  up  and  down.  Notice  the  motion  of  the  inter- 
costals during  this  process. 

Insert  the  glass  tube  in  the  top  of  the  windpipe  through 
the  throat  opening,  and  blow  gently  through  this  tube. 
Observe  the  motion  of  the  ribs  and  the  motion  of  the  muscu- 
lar diaphragm  that  forms  the  partition  between  the  ab- 
dominal and  thoracic  cavities.  Press  the  diaphragm  up  with 
the  finger  and  note  that  air  is  forced  out  of  the  tube. 

Now  cut  the  ribs  where  they  join  the  breast  bone,  and  press 
them  back  to  expose  the  organs  of  the  cavity.  Sketch  the 
position  of  the  lungs  and  heart.  Compare  with  Fig.  35, 
page  76.  Note  the  texture  of  the  lungs  and  observe  the 
windpipe  (trachea)  with  its  cartilage  rings.  (These  are  nec- 
essary to  prevent  collapse  of  the  tube.)  How  is  the  windpipe 
connected  with  the  lungs? 

Carefully  dissect  out  the  lungs  and  windpipe  and  float 
them  in  water.  Cut  them  at  the  entrance  of  the  windpipe 
and  trace  out  the  bronchi  and  their  branches.  •  How  do  these 

90 


RESPIRATION  91 

branches  end?  (This  large  amount  of  branching  allows  the 
air  to  be  brought  in  contact  with  very  many  small  blood 
vessels,  through  the  walls  of  which  oxygen  is  absorbed  by 
the  blood.) 


LIX. — MECHANICS  OF  RESPIRATION. 

Apparatus. — A  glass  bell  jar  open  at  the  top,  a  glass  tube  with 
a  toy  balloon  firmly  bound  to  one  end,  a  stick  with  a  knob,  a  piece 
of  sheet  rubber,  a  one-holed  stopper  to  fit  top  of  bell  jar. 

Directions. — Pass  the  tube  through  the  stopper  and  seal 
it  in  place  with  wax.  Insert  the  stopper  in  the  top  of  the 
bell  jar  with  the  balloon  inside  the  jar.  Tie  the  knob  into 
the  center  of  the  rubber  sheet  and  fasten  the  latter  tightly 
across  the  base  of  the  bell  jar,  leaving  the  stick  outside  to 
serve  as  a  handle.  With  this  arrangement  the  tube  cor- 
responds to  the  trachea,  the  balloon  to  the  lungs,  the  rubber 
sheet  to  the  diaphragm,  and  the  jar  to  the  thoracic  cavity. 

Now  move  the  handle  downward  so  as  to  stretch  the 
diaphragm.  What  happens  to  the  balloon?  What  causes 
this  action?  Move  the  handle  upward.  What  happens  to 
the  balloon  now?  Why?  How  does  the  diaphragm  secure 
rhythmic  inhaling  and  exhaling,  i.  e.}  inflow  and  outflow  of 
air?. 

LX. — STUDY  OF  EXPIRED  AIR. 

Apparatus. — Chemical  thermometer,  limewater,  test  tube,  glass 
tube,  large-mouthed  bottle,  pneumatic  trough. 

Directions.— A .  Temperature.  Breathe  on  the  bulb  of  the 
thermometer  and  determine  the  temperature  of  the  expired 
air.  Place  the  bulb  under  the  tongue  and  determine  the  body 


92  EXPERIMENTAL  PHYSIOLOGY 

temperature.  How  does  the  temperature  of  the  expired  air 
compare  with  that  of  the  body,  or  blood  temperature?  Test 
this  on  several  successive  days  and  note  whether  the  tem- 
perature varies  with  the  external  temperature  or  is  con- 
stant. 

B.  Composition.  Breathe  on  a  piece  of  glass.  What  col- 
lects on  the  surface?  Does  expired  air  contain  more  or  less 
moisture  than  inspired  air? 

Fill  the  test  tube  half  full  of  limewater  and  blow  the 
breath  gently  through  it  by  means  of  the  glass  tube.  What 
change  takes  place  in  the  limewater?  What  does  this  in- 
dicate? (See  Ex.  V.) 

Fill  the  bottle  with  expired  air  by  the  method  of  Ex.  II. 
Turn  the  bottle  mouth  upward  and  introduce  a  lighted 
match  into  it.  Does  the  match  continue  to  burn?  What 
does  this  indicate?  (Air  expired  in  ordinary  breathing  has 
lost  about  one-fourth  of  the  oxygen  contained  in  the  air 
inspired.) 


EXCRETION 


LXI. — STUDY  OF  *A  LAMB'S  KIDNEY  (OPTIONAL). 

Apparatus. — A  fresh  lamb's  kidney  with  its  capsule  of  fat,  scalpel. 

Directions. — Carefully  remove  the  outer  layer  of  fat  and 
the  membranous  inner  capsule.  What  is  the  function  of  this 
material?  (A  dissection  of  the  rat  makes  a  good  demon- 
stration of  the  location  of  the 
kidneys  and  their  relation  to 
ureter  and  bladder.)  Cut  the 
kidney  lengthwise  so  as  to  split 
the  ureter  where  it  emerges  from 
the  concave  side.  On  the  cut 
surface  make  out  the  pale  inner 
striated  medulla  and  its  pyramids 
of  Malpighi,  the  outer  cortex,  and 
the  intermediate  layer  between  the 
two.  Note  also  the  enlarged  upper 
end,  or  pelvis,  of  the  ureter;  the 

Cavity,    Or     sinUS,     into     Which     it    FIG.  44.— Diagram  of  a  Longitu- 

opens;  and  the  tubes,  or  calices,     ^j  ^J^  °*  ^a^ntS  I', 

between        the       projecting       pyra-        glomerulus;  t,  uriniferous  tubule; 

,        v,  renal  vein. 

mids.    Note  also  the  entrance  of 

the  renal  artery  into  the  kidney,  and  the  renal  vein,  just 

above  the  ureter.    From  the  accompanying  Fig.  44  make 

93 


94  EXPERIMENTAL   PHYSIOLOGY 

out  the  parts  which  act  in  removing  the  waste.  (The  artery 
brings  in  the  blood,  which  gives  up  its  waste  in  the  glomer- 
ulus.  This  waste  is  collected  by  the  tubule  and  emptied  by 
it  into  the  ureter.  The  capillaries  collect  the  blood  which 
has  been  cleared  of  its  waste,  and  return  it  to  the  vein.) 

NOTE. — Prepared  sections  of  injected  and  stained  cortex  may  be 
shown  and  the  following  parts  demonstrated:  Malpighian  bodies, 
uriniferous  tubules,  and  capillaries. 


LXII. — STUDY  OF  THE  SKIN. 

Apparatus. — Prepared  slide  of  epidermis  (that  from  the  sole  of 
the  foot  preferred,  from  its  thickness),  a  vertical  section  of  a  hair, 
compound  microscope,  needle,  scissors. 

Directions.— A.  Surface  Study  of  the  Skin  Layers.  Ster- 
ilize a  needle  by  holding  it  in  a  flame  a  moment.  Run  it 
carefully  under  the  thin  outer  layer  of  skin  at  the  base  of 
the  thumb.  (This  layer  is  ca'lled  the  cuticle  or  epidermis.) 
Does  the  wound  cause  any  pain?  Are  there  any  nerves  in 
this  layer?  Does  the  wound  bleed?  Does  the  epidermis 
contain  any  blood  vessels?  With  the  needle  tear  off  a  little 
of  this  epidermis.  What  is  its  color?  consistency?  Where 
is  it  thickest  on  the  hand?  Why?  Where  else  on  the  body 
do  you  find  similar  thickening? 

What  is  the  color  of  the  skin  layer  (dermis)  'under  this 
epidermis?  Prick  it  with  the  needle.  Is  it  sensitive? 
Does  it  contain  blood  vessels?  Examine  its  surface  and  note 
that  it  is  ridged.  A  magnifier  will  show  that  these  ridges 
are  made  up  of  a  series  of  points,  or  papillce.  (Each  papilla 
marks  the  end  of  a  nerve  of  touch.  These  nerve  endings 
are  called  on  that  account  tactile  organs;  see  Fig.  45.) 


EXCRETION 


95 


Pick  up  a  little  of  the  skin  between  the  fingers.  Is  it  at- 
tached to  the  underlying  muscles?  About  how  thick  is  it 
on  the  back  of  the  hand?  on  the  base  of  the  thumb? 


Sweat-Duct 


Sebaceous  Gland 


Horny  layer 
Pigment  layer 


Tactile  Organ 

Nerve- 
Blood  Vessels 

Sweat  Oland--^- 

Fat 


Epidermis 


Dermis 


FIG.  45.— Diagram  of  Skin  Section. 


B.  Microscopic  Study  of  a  Section.    Study  the  prepared 
slide,  under  the  high  power.     Note  the  layer  character  of 
the  epidermis,  the  papillae  with  their  blood  vessels,  the  coiled 
sweat  glands  and  their  ducts  (thick  sections  show  these  best) . 
Sketch  and  label  all  parts  of  your  drawing  as  in  the  dia- 
gram. 

Compare  the  action  of  the  sweat  glands  with  that  of  the 
tubuli  uriniferse  (uriniferous  tubules)  of  the  cortex  of  the 
kidneys.  When  do  we  perspire  most?  Why  does  exercise 
increase  the  amount?  What  is  one  function  of  the 
skin? 

C.  Study   of    Skin  Modifications,     (a)  Hairs.   Note   the 


96 


EXPERIMENTAL  PHYSIOLOGY 


location  of  hair  on  the  head.    What  is  its  function?    Ex- 
amine one  of  the  hairs  on  the  back  of  the  hand.     Cut  it.     Is 

it  sensitive?  Pull  it.  Where  is 
the  sensitive  portion  located  ? 
Where  is  the  seat  of  growth  ? 
What  part  of  the  skin  is  it  most 
like? 

Study  the  slide  showing  a  ver- 
tical section  of  a  hair,  under  the 
low  power  of  the  microscope. 
Note  that  the  hair  is  imbedded  at 
the  base  in  a  skin  follicle,  and 
grows  from  a  skin  papilla  at  the 
bottom  of  this  follicle.  Note  also 
the  sebaceous  or  oil  glands  that 
serve  to  coat  the  hair  with  oil. 

(6)  Nails.  Make  a  drawing  of 
your  finger  nail,  showing  all  areas. 
What?  parts  are  attached  to  the 
skin?  Why  is  the  part  under  the 
nail  called  the  " quick"?  What  is 
one  function  of  the  nail?  Cut 
it.  Is  it  sensitive  ?  Pull  it. 
Where  is  its  sensitive  part  located? 
How  does  it  compare  with  the  hair 
in  this  respect?  Cut  a  nick  in  it 
and  examine  it  from  day  to  day. 
Does  it  change  position?  Where 


FIG.46.-Hair-follicleinLongi 

tudinal  Section:  h,  hair  shaft,  dO6S  the  growth  of  the  nail  OCCUr? 
showing  its  medulla  or  core;          miij.  n       j  i          /•          ,•  f 

s,  sebaceous  giand;  w,  sheath       I  abulate    all    the   functions    of 

of  skin; /fatty  tissue.  (At  the  ^airs,    nails,    and    skin    that  you 

base  of    the,  hair  is    seen  the 

papilla  that  forms  it.)  have  learned. 


NERVOUS  SYSTEM 


LXIII. — DISSECTION  OF  SHEEP'S  BRAIN. 

Apparatus. — Sheep's  head,  bone  forceps,  hammer,  scalpel,  needle, 
forceps,  50%  alcohol. 

Directions.—^.  To  Remove  Brain  from  Skull.  Strike 
the  top  of  the  skull  with  the  hammer  so  as  to  crack  the 
bone,  but  not  to  force  it  into  the  brain;  and  then  carefully 
remove  the  pieces  with  the  bone  forceps.  Be  careful  not 
to  injure  the  underlying  membrane  (dura  mater)  which 
lines  the  skull  and  covers  the  brain.  After  the  top  of  the 
skull  is  removed  slit  this  dura  mater  around  the  edge,  and 
remove  it,  exposing  the  brain.  Note  that  over  the  surface 
of  the  brain  is  another  membrane,  the  pia  mater.  Now 
carefully  lift  the  brain  from  the  floor  of  the  skull,  beginning 
at  the  front.  Notice  that  it  is  bound  by  nerves  and  portions 
of  the  dura  mater.  Cut  these  nerves,  leaving  as  long  ends 
as  possible,  and  do  not  cut  off  the  olfactory  lobes  which  are 
on  the  under  side  of  the  brain.  Place  the  brain  in  50% 
alcohol  to  harden,  for  several  days.1 

B.  The  Coverings  of  the  Brain.  Tear  off  a  little  of  the 
dura  mater  with  the  forceps.  Does  it  tear  easily?  Are 
both  sides  of  it  smooth?  Where  are  its  blood  vessels? 
What  do  they  feed? 

Pick  up  a  little  of  the  pia  mater  (brain  cover)  with  the 

i  Preserve  the  skull,  with  eyes,  for  use  in  Ex.  LXX. 
97 


98 


EXPERIMENTAL   PHYSIOLOGY 


needle  point.     Is  it  thicker  or  thinner  than  the  dura  mater? 
Where  are  its  blood  vessels?    What  do  they  feed?    What 
are  the  functions  of  the  three  coverings  of  the  brain? 
C.  The  External  Parts  of  the  Brain.    Examine  the  top  of 

the  brain.  Note  the  two 
convoluted  hemispheres  into 
which  the  fore  brain  (cere- 
brum) is  divided  by  a  fissure 
(the  longitudinal  fissure) . 
Back  of  this  appears  the 
wrinkled  surface  of  the  hind 
brain  (cerebellum).  Is  this 
divided? 

Turn  the  brain  over  and 
examine  the  lower  surface. 
Note  the  olfactory  lobes  on 
the  front  part  of  the  hemi- 
What  is  their  func- 
Back  of  these,  locate 
the  optic  nerves  and  note  how  they  crc3S  to  form  a  chiasma, 
so  that  the  right  eye  is  controlled  by  the  left  hemisphere,  and 
vice  versa.  Just  back  of  this  may  be  seen  the  pons,  or  bridge, 
that  connects  the  two  sides  of  the  cerebellum,  and,  coming 
out  in  front  of  it  on  each  side,  the  stalks  (crura  cerebri)  which 
spread  out  into  the  two  hemispheres  of  the  cerebrum. 
Note  that  the  stalks  are  the  forward  projections  of  a  conical 
spinal  bulb,  which  comes  between  the  cerebellum  and  the 
pons,  and  is  continued  backward  into  the  spinal  cord. 
This  bulb  is  a  part  of  the  hind  brain,  and  is  called  the  me- 
dulla. All  along  the  under  side  of  the  brain  are  located  the 
cranial  nerves,  occurring  in  pairs.  Beginning  at  the  front 
locate  the  pairs  named  in  the  following  table: 


FIG.  47. — Upper  Surface  of  Brain  (Hu- 
man): 1,  2,  two  halves,  or  hemispheres, 
of  cerebrum;  3,3,  longitudinal  fissure. 


NERVOUS   SYSTEM 


99 


Olfactory  Bulb 

(to  which  is  attached 
the  Olfactory  Nerve) 

Pituitary  Body _^_ 

Optic  Ne  rve-  — 

Optic  Chiasma — — 
Oculomotor  Nerve — __. 

Trochlear  Nerve 

Trigeminal  Nerve 

Pons  Varolii — _ 

Abducens  Nerve-  _ 

Facial  Nerve — 

Auditory  Nerve-  _ 

Glossopharyngeal  Nerve  __ 

Vagus  Nerve — 

Spinal  accessory  Nerve — 

Hypoglossal  Nerve- - 

Medulla  Oblongata 

First  Sjjinal  Nerve — 
Cerebellum — 
Spinal  Cord — 
Second  Spinal  Nerve 


FIG.  48. — Under  Surface  of  Brain  (Human). 


NAME. 

FUNCTION. 

1st  pair 

Olfactory 

Smell  —  Sensory 

2d    pair 

Optic 

Sight  —  Sensory 

3d    pair 

Oculomotor 

Eye  Muscles  —  Motor 

4th  pair 

Trochlear 

Eye  Muscles  —  Motor 

5th  pair 

Trigeminal 

Facial  —  Sensory  and  Motor 

Cth  pair 

Abducens 

Eye  Muscles  —  Motor 

7th  pair 

Facial 

Motor 

Sth  pair 

Auditory 

Hearing  —  Sensory 

9th  pair 

Glossopharyngeal 

Tongue    and    throat  —  Sensory    and 

Motor 

10th  pair 

Vagus 

Thorax    and    abdomen  —  Sensory    and  Motor 

llth  pair 

Spinal  Accessory 

Sensory  and  Motor 

12th  pair 

Hypoglossal 

Tongue  —  Motor 

D.  Vertical  Section  (right  side).  Cut  the  brain  through 
lengthwise,  parallel  to  the  line  of  the  longitudinal  fissure,  but 
one-sixteenth  of  an  inch  to  the  left  of  this  line  in  order  not 
to  cut  the  septum.  Examine  the  right  side.  Note  the 


100 


EXPERIMENTAL   PHYSIOLOGY 


white,  fibrous  body  (corpus  callosum)  which  unites  the  two 
hemispheres.  In  the  front  part  of  this  are  seen  the  thin 
membranes  (septum  lucidum)  which  inclose  between  them 


JForamen  of  Monro 


Optic  Chiasma 

Pituitary  Body 

Oculomotor  Nerve 

Fons  Varolii 


Medulla  Oblongata    / 
Fourth  Ventricle 


Spinal  cord 


FIG.  49. — Section  of  Brain. 

a  portion  actually  outside  the  brain,  but  often  called  the 
" fifth"  ventricle.  Below  this  is  the  fornix,  which  forms  the 
roof  of  a  true  brain  cavity — the  third  ventricle — whose 
sides  are  the  optic  thalami.  This  ventricle  projects  forward 
into  a  funnel  called  the  infundibulum.  In  the  center  of  this 
ventricle  is  a  round  body  (the  median  commissure)  which 
was  cut  through  by  the  section.  In  front  of  this  is  a 
small  aperture  (the  foramen  of  Monro)  that  connects  this  cav- 
ity with  a  cavity  in  the  right  hemisphere.  The  floor  of  the 


NERVOUS  SY&T'EM  ;  ]U)i 


third  ventricle  is  formed  by  the  crura  cerebri,  which  extend 
backward,  between  the  pons  and  cerebellum,  into  the  spinal 
bulb  or  medulla,  and  this,  in  turn,  backward  into  the  spinal 
cord.  At  the  back  of  the  third  ventricle  note  that  a  tube  or 
canal  (aqueduct)  connects  it  with  a  much  smaller  cavity  (the 
fourth  ventricle)  just  under  the  cerebellum.  Four  little 
bodies  (the  corpora  quadrigemina)  form  the  roof  of  this  tube 
between  the  fornix  and  cerebellum.  Note  the  tree-like  inter- 
nal structure  of  the  cerebellum.  What  causes  its  wrinkled 
surface? 

Note  the  gray  and  the  white  matter  that  make  up  the 
cerebrum.  Where  is  the  gray  matter  located?  the  white? 

NOTE.— The  first  ventricle  in  the  olfactory  "lobes  and  the  lateral 
ventricle  may  be  shown  by  suitable  sections,  if  desired,  and  the  re- 
lation of  these  may  be  brought  out  by  the  aid  of  diagrams  of  the 
simple  brain  structure. 


LXIV.— DISSECTION  OF  SPINAL  CORD. 

Apparatus. — Thin  section  of  cervical  portion  of  spinal  cord,  glyc- 
erine, slides,  cover  glass,  compound  microscope. 

Directions. — (Prepare  sections  by  placing  a  piece  of  the 
cervical  spinal  cord  for  three  or  four  weeks  in  Miiller's  fluid 
[2  J  parts  of  potassium  bichromate,  1  part  of  sodium  sulphate, 
100  parts  of  water].  Then  wash  it  with  water  and  place  it 
in  30%  alcohol  for  a  few  days.  Then  transfer  it  to  95% 
alcohol.  Cut  a  thin  cross  section  and  mount  it  in  glycerine. 
Cover  it  with  a  cover  glass). 

Examine  under  the  low  power.  Note  the  outer  covering 
of  pia  mater.  Note  the  distribution  of  the  gray  and  white' 
matter.  Sketch  it.  Is  it  the  same  as  in  the  brain?  Note 


102 


EXPERIMENTAL   PHYSIOLOGY 


the  division  into  two  parts  by  a  deep  anterior,  and  shallow 
posterior  fissure.  Note  also  two  fissures  in  each  half  (an- 
terior and  posterior  lateral)  through  which  the  central  gray 
mass  reaches  the  surface.  The  gray  masses  in  each  half  of 


Posterior 


FIG.  50. 

the  cord  may  be  seen  to  be  united  by  a  commissure  that 
incloses  the  central  or  neural  canal.  Note  the  cellular  char- 
acter of  the  gray  matter.  The  gray  matter  that  forms  the 
posterior  horns  forms  the  core  of  spinal  nerves  of  the  sort 
called  afferent.  The  anterior  horns  form  the  core  of  effer- 
ent nerves.  (Afferent  nerves  carry  messages  to  the  cord, 
efferent  away  from  it.)  The  white  matter  covers  these  and 
they  unite  outside  in  a  common  spinal  nerve.  (See  Fig.  50.) 
For  structure  of  a  neuron,  see  Ex.  XXVIII. 


SPECIAL   SENSES 


LXV. — NERVE  ACTION. 

Apparatus. — A  stop  watch,  pencil,  paper. 

Directions. — Let  the  teacher  write  a  vowel  on  a  piece  of 
paper  which  he  shall  keep  covered.  Arrange  the  class  in  a 
circle.  Station  a  boy  beside  the  teacher  with  a  stop  watch. 
Proceed  as  follows:  The  teacher  shows  the  vowel  to  the 
pupil  on  his  right,  who  whispers  it  to  the  pupil  on  his  right  as 
quickly  as  possible,  and  so  on  around  the  circle  to  the  teacher 
again.  All  this  as  rapidly  as  possible.  Let  the,  boy  with 
the  watch  release  the  stop  at  the  second  when  the  teacher 
exposes  the  letter  to  the  pupil  on  his  right,  and  stop  it  again 
when  the  last  pupil  repeats  the  letter  to  the  teacher.  Divide 
the  time  elapsed  by  the  number  of  pupils.  The  result  will 
represent  the  average  reaction  time  of  each  pupil.  Change 
the  arrangement  of  the  pupils  and  note  whether  the  time 
varies.  What  muscular  action  does  each  pupil  perform  in 
receiving  and  transmitting  the  sound?  What  sensory  nerves 
are  employed^?  what  motor  nerves? 

NOTE. — In  order  to  bring  out  various  sensation  reactions  this  ex- 
periment may  be  varied  in  many  ways  which  will  suggest  them- 
selves to  the  teacher. 

103 


104  EXPERIMENTAL   PHYSIOLOGY 

LXVI. — CUTANEOUS  SENSATIONS. 

Apparatus. — A  pair  of  metal  compasses,  toothpicks,  a  dish  of 
boiling  water,  a  dish  of  ice  water,  pen  and  ink. 

Directions. — One  pupil  should  operate,  another  acting 
as  subject.  The  subject  should  be  blindfolded. 

A.  Touch.     Sharpen  the  ends  of  the  toothpicks  and  tie 
one  to  each  arm  of  the  compass.     What  is  the  least  distance 
apart  at  which  the  two  points  may  be  held  and  felt  as  two 
points,  when  applied  to  the  tips  of  the  fingers?  the  tip  of  the 
tongue?  back  of  the  hand?  forearm?  back  of  the  neck? 
Record   the  results.     Are  all  parts  of  the  body  equally 
sensitive   to   touch?    Which  parts  are  most  sensitive? 

B.  Temperature.    Dip  a  metal  point  of  the  compasses  in 
cold  water  and  move  it  lightly  over  the  back  of  the  hand. 
Does  it  feel  equally  cold  to  all  parts  of  the  skin?    Mark 
with  an  ink  dot  those  points  where  the  sensation  is  most  acute. 
Now  dip  the  metal  point  in  the  hot  water  and  move  it  over 
the  same  area.     Locate,  as  before,  the  spots  where  sensation 
is  most  acute.     Do  the  hot  and  cold  spots  coincide?    What 
do  you  conclude  about  the  temperature  sensation  power 
of  the  skin?    Is  it  a  general  or  a  localized  sensitive  power? 
Test  other  areas  of  the  body  in  the  same  way.     Are  the 
temperature  spots  equally  numerous  in  all  parts?    Where 
are  they  most  numerous?   least  numerous? 

LXVII. — STUDY  OF  THE  TONGUE. 

Directions. — Protrude  the  tongue  as  far  as  possible  and 
with  the  aid  of  a  mirror  examine  its  surface".  Note  the 
raised  points  (the  papillce)  on  the  surface.  Observe  that 
they  are  of  three  forms:  long  and  slender  (filiform),  mush- 


SPECIAL  SENSES  105 

room-topped  (jwngiform),  and  large  and  wartlike  (circum- 
vallate).  Draw  an  outline  of  the  tongue  and  locate  on  it 
the  regions  where  these  different  forms  are  to  be  found. 

LXVIII. — SENSATIONS  OF  TASTE  AND  SMELL. 

Apparatus. — Onion,  sugar,  salt,  vinegar,  dilute  ammonia,  quinine. 

Directions. — A.  Location  of  Taste.  Wipe  the  tongue 
dry  and  place  on  its  tip  a  little  dry  sugar.  Has  it  any  taste? 
Let  it  dissolve.  Has  it  any  taste  now?  Repeat,  placing 
the  sugar  at  the  back  of  the  tongue.  Is  its  sweetness  more 
or  less  prominent?  Repeat  again,  using  quinine,  vinegar,  and 
salt  successively.  Where  are  the  sensations  of  bitterness, 
sourness,  and  saltiness  most  prominent? 

B.  Taste  and  Odor.  Examine  the  various  substances 
named  under  "  Apparatus."  Which  have  taste?  odor? 
Place  each  of  these  substances  on  the  tongue  of  a  pupil 
who  has  been  previously  blindfolded,  and  who  is  holding 
his  nose  tightly.  Record  the  substances  recognized  by 
taste  alone.  Repeat,  leaving  the  nose  free  but  retaining  the 
blindfold.  Record  those  substances  recognized  by  smell 
alone;  by  taste  and  smell  combined. 

LXIX.— HEARING;  LAWS  OF  SOUND  (OPTIONAL). 

Apparatus.— Stretched  wire,  bridge  to  shorten  length. 

Directions — A.  Strike  the  wire.  Do  you  get  any  sound? 
What  is  the  wire  doing?  All  sound  depends  upon  vibra- 
tion :  test  several  sounding  bodies  to  verify  this  statement. 

B.  Move  the  bridge  to  the  middle  point  of  the  wire  and 
strike  again.  Is  the  pitch  higher  or  lower?  Does  a  short 


106  EXPERIMENTAL   PHYSIOLOGY 

string  vibrate  faster  or  slower  than  a  long  one?    What  effect 
has  rate  of  vibration  on  the  pitch  of  a  sound? 

C.  Strike  the  wire  gently.    Note  the  distance  at  which 
the  sound  can  be  heard.     Strike  harder.     Is  the  tone  louder 
or  softer?    Can  it  be  heard  at  a  farther  distance?    Does  it 
vary  in  pitch?    What  effect  on  sound  does  extent  (ampli- 
tude) of  vibration  have? 

D.  Stand  at  the  point  where  you  can  just  hear  the  tick- 
ing of  a  watch.     Now  make  a  conical  tube  of  paper  and 
insert  the  small  end  in  the  ear.     Point  the  large  end  toward 
the  watch.     Can  you  hear  it  any  better  now?    What  part 
of  the  ear  serves  a  purpose  similar  to  that  of  the  tube? 

LXX. — VISION;  DISSECTION  OF  SHEEP'S  EYE. 

Apparatus. — Sheep's  skull  with  eyes  in  socket  (the  skull  used 
in  Ex.  LXIII  will  serve  for  this  purpose),  scalpel,  scissors,  bone 
forceps,  evaporating  dish. 

Directions. — Cut  away,  with  the  bone  forceps,  the  bones 
that  inclose  the  eye,  so  that  it  may  be  seen  in  position  from 
the  side. 

A.  Muscles.  Notice  that  the  motion  of  the  eyeball  is  con- 
trolled by  six  muscular  bands.  Locate  the  attachment  of 
four  of  these  bands  on  the  top  (superior  rectus),  bottom 
(inferior  rectus) }  side  near  nose  (internal  rectus),  and  side 
farthest  from  nose  (external  rectus).  Note  that  these  ex- 
tend directly  backward  to  the  end  of  the  socket  and  have 
their  origin  there.  What  motions  do  these  muscles  give  to 
the  eyeball?  Now  locate  on  the  top  of  the  eyeball  the  at- 
tachment of  a  transverse  band  of  muscle  (the  superior  ob- 
lique) and  follow  its  course,  through  a  tendon  pulley,  to 
its  origin  at  the  back  of  the  socket.  In  what  direction 


SPECIAL   SENSES  107 

does  its  contraction  take  place?  What  motion  does  it  give 
to  the  eye?  On  the  under  side  of  the  eye  locate  another 
transverse  muscle  (the  inferior  oblique).  Where  is  its  ori- 
gin? Has  it  a  pulley? 

B.  The  Externals  of  the  Eye.    Cut  the  muscle  bands  and 
trim  away  a  white  membrane  (the  conjunctiva,  a  continua- 
tion of  the  lining  of  the  eyelid)  in  the  front  of  the  eye.    Note 
that  the  eye  is  still  attached  to  the  socket  by  a  cord,  just 
below  and  outside  the  center  of  its  rear  surface.    This  is  the 
optic  nerve,  which  enters  the  eye  here  from  the  brain.    Pull 
the  eye  out  of  the  socket  and  cut  this  cord.     Now  examine 
the  outside  of  the  eyeball.     Note  that  it  is  covered  with  a 
firm  white  coat  (the  sclerotic)  except  in  the  front,  where 
there  is  a  clear  layer,  the  cornea,  usually  dulled  in  death. 

C.  The  Internals  of  the  Eye.    Hold  the  eye  with  the  cornea 
uppermost,  and  remove  this  with  the  scalpel  by  cutting  hori- 
zontally around  its  edge.    The  liquid  back  of  this  layer  is 
the  aqueous  humor.     Directly  back  of  the  cornea  appears  a 
circular  muscular  curtain — colored  in  the  human  eye — called 
the  iris,  and  in  its  center  a  hole — the  pupil.    What  conclu- 
sions do  you  draw  as  to  the  functions  of  this  iris  from  compar- 
ing the  size  of  the  pupil  of  your  own  eye,  when  looking  at  a 
bright  light,  with  its  size  when  in  a  dimly  lighted  room? 
Is  its  action  voluntary? 

Now  lay  the  eye  upon  its  side  in  the  evaporating  dish 
and  cover  it  with  water.  With  the  scalpel  cut  a  section 
through  the  entire  eye,  splitting  the  optic  nerve  (see  Fig. 
51).  Observe  the  following  parts:  just  back  of  the  iris 
the  convex  crystalline  lens  and  its  capsule;  the  muscles  that 
control  the  shape  of  the  lens— the  ciliary  muscles— and  their 
ligamentous  attachment  (suspensory  ligament) ;  on  the  inside 
of  the  layers  that  form  the  walls  of  the  eye,  at  the  edge  of 


108  EXPERIMENTAL   PHYSIOLOGY 

the  lens,  a  black,  ridged  membrane  (the  ciliary  process) ;  the 
jelly-like  mass  that  fills  the  body  of  the  eye  (vitreous  humor) ; 
the  three  layers  of  the  wall  of  the  eyeball — outer  (sderotic)} 
middle  (choroid),  inner  (retina). 

Note  that  the  optic  nerve  pierces  the  two  outer  coats  and 
spreads  out  to  form  the  retina.  Remove  the  vitreous  humor 
and  notice  the  soft,  whitish  retina.  Tear  this  out  with  the 

/Sc 


FIG.  51. — Cross  Section  of  the  Eye:  Con,  conjunctiva;  Sc,  sclerotic;  C,  cornea;  A, 
aqueous  humor;  /,  iris;  L,  crystalline  lens;  Cm,  ciliary  muscles  and  ligament; 
CP,  ciliary  process;  V,  vitreous  humor;  Ch,  choroid;  R,  retina;  O,  optic  nerve. 

forceps  and  note  its  consistency  and  thickness.  Under  this 
observe  the  color  and  luster  of  the  choroid  coat.  When 
this  is  torn  out,  the  interlacing  blood  vessels  are  seen  passing 
from  one  layer  to  the  other. 

LXXI. — ACTION  OF  THE  EYE. 
Apparatus. — Model  of  eye. 
Directions. — Construct  a  model  of  the  eye  as  follows: 


SPECIAL   SENSES 


109 


Obtain  a  wooden  box  eighteen  or  twenty  inches  long  and 
about  eight  inches  wide  and  deep.  Leaving  one  side  open, 
paint  the  inside  of  the  box  black.  Around  the  open  side 
tack  a  piece  of  black  cloth  large  enough  to  cover  the  head 
of  the  observer  and  shut  out  the  light  from  the  interior  of 
the  box.  At  one  end  of  the  box  cut  a  hole  one  inch  in  di- 
ameter. Cut  several  black  cardboard  disks  to  fit  this'  aper- 
ture, and  perforate  their  centers  with  holes  varying  from 
one-sixteenth  to  one-half  inch  in  diameter.  Mount  a  con- 
vex lens  in  a  movable  holder  which  can  be  moved  forward 
and  backward  on  the  floor  of  the  box,  and  which  will  bring 
the  center  of  the  lens  opposite  the  center  of  the  hole.  Mount 


Screen  (Retina) 


Lena 


FIG.  52. 


a  piece  of  ground  glass  in  the  same  way  to  serve  as  a  screen. 
Arrange  all  parts  as  in  Fig.  52. 

The  cardboard  disks  will  then  correspond  to  the  iris  with 
its  pupil;  the  walls  of  the  box  to  the  sclerotic;  the  black 
paint  to  the  choroid  (what  is  its  function?);  the  lens  to 
the  crystalline  lens,  and  the  screen  to  the  retina.  A  watch 
glass  placed  on  the  aperture  would  resemble. the  cornea. 

A.  Action  of  Parts.  Darken  the  room  and  place  a  lighted 
candle  at  a  distance  of  three  feet  from  the  aperture.  Place 
in  the  aperture  the  disk  with  one-quarter  inch  perforation. 
Cover  head  with  cloth  and  place  screen  at  the  rear  of  the 


110  EXPERIMENTAL   PHYSIOLOGY 

box.  Now  move  the  lens  back  and  forth  until  there  ap- 
pears on  the  screen  a  sharp  image  of  the  candle  flame.  Is 
it  right  side  up?  What  is  the  function  of  the  lens?  Mark 
position  of  lens  and  screen.  Move  the  candle  three  feet 
farther  away.  Does  the  image  remain  on  the  screen?  Keep- 
ing the  lens  fixed,  move  the  screen  forward  in  the  box  until 
the  distinct  image  appears  again.  Return  the  screen  to  its 
original  position  and,  by  moving  the  lens,  cause  the  same 
result — an  image  on  the  screen.  Which  is  adjustable  in 
the  eye — the  screen  (retina)  or  lens?  How  is  the  lens  ad- 
justed in  the  eye?  (This  adjustment  of  the  lens  to 'the  dis- 
tance of  objects  is  called  accommodation.)  Change  the  disks 
in  the  aperture,  using  first  larger  and  then  smaller  openings. 
Which  gives  the  brightest  image?  What  is  the  function  of 
the  iris? 

NOTE. — By  using  external  lenses  as  "spectacles,"  short-  and  long- 
sightedness can  be  corrected  and  illustrated. 


BACTERIA 
LXXII. — STUDY  OF  BACTERIA. 

Apparatus. — Hay,  milk,  meat,  test  tubes  with  corks  to  fit,  slides, 
cover  glasses,  compound  microscope,  sterilized  absorbent  cotton, 
methyl  green,  corrosive  sublimate. 

Directions..— A.  Prepare  three  test  tubes  as  follows: 
Put  in  one  some  pieces  of  chopped  hay  and  cover  with  water; 
in  the  second  some  milk;  in  the  third  some  meat,  covered 
with  water.  Let  these  stand  uncovered,  in  a  warm  place, 
for  several  days.  Describe  the  changes  that  take  place  in 
the  appearance  and  odor  of  the  contents.  Note  the  scum 
that  appears  on  the  surface.  Mount  some  of  this  scum  on 
a  slide  and  cover  with  a  cover  glass.  Examine  with  the 
high  power  of  the  microscope.  Note  the  masses  of  moving 
forms  (bacteria)  that  make  up  this  scum.  Sketch  the  shape 
of  some  of  these  bodies.  (If  a  drop  of  methyl  green  be  run 
under  the  cover  glass,  the  structure  will  be  clearer.) 

B.  Prepare  four  tubes  as  follows:  Fill  each  tube  with 
milk.  Pack  one  in  ice;  leave  the  top  open  and  label  it 
No.  1.  Boil  the  contents  of  the  second,  stopper  with  a  cork 
that  has  been  boiled  in  water,  and  leave  in  a  warm  place; 
label  this  No.  2.  Boil  the  contents  of  the  third  one  and 
stopper  with  sterilized  absorbent  cotton;  label  this  No.  3. 
Place  No.  3  with  No.  2.  Place  the  fourth,  labelled  No.  4,  in 
a  warm  place,  uncorked.  After  several  days  examine  the 

111 


112  EXPERIMENTAL   PHYSIOLOGY 

four  tubes.     In  which  is   the  milk  still  fresh?    What  is 
the  effect  of  heat  on  bacteria?  of  cold? 

Remove  the  stopper  from  No.  2  and  the  ice  from  No.  1, 
and  place  with  No.  3  for  several  days  longer.  After  that 
time  examine  the  tubes.  In  which  is  the  milk  still  fresh? 
From  these  experiments,  what  are  your  conclusions  as  to 
the  source  of  bacteria?  Is  air  that  is  freed  from  bacteria 
by  being  strained  through  cotton,  a  cause  of  decay? 

C.  Prepare  two  tubes  as  follows:  Boil  some  milk  and  fill 
two  tubes  that  have  been  previously  boiled  in  water.  Stop- 
per with  sterilized  cotton  and  allow  the  tubes  to  cool  to 
room  temperature.  Now  introduce  hi  to  one  tube  some  scum 
from  the  hay  infusion  and  res  topper  quickly.  Set  it  in  a 
warm  place.  Prepare  a  two  per  cent  solution  of  corrosive 
sublimate.  Mix  a  teaspoonful  of  this  with  some  scum  from 
the  hay  infusion  and  let  it  stand  for  ten  minutes.  Then 
introduce  this  into  the  second  tube  and  stopper  again  quickly  ' 
with  the  cotton.  Place  it  with  the  other  tube.  Examine 
after  a  day.  In  which  tube  has  the  milk  decomposed?  What 
must  the  corrosive  sublimate  have  done  to  the  bacteria? 
What  substance  may  be  used  to  kill  bacteria  in  place  of 
heat?  Killing  bacteria  by  heat  is  called  sterilizing;  chemical 
substances  that  perform  the  same  action  are  called  antisep- 
tics. What  are  some  of  the  common  antiseptics? 

Summarize  your  results  under  the  following  heads :  (1)  con- 
ditions favorable  to  bacteria  growth;  (2)  conditions  unfavor- 
able to  bacteria  growth;  (3)  methods  of  killing  bacteria. 


OUTLINES    OF    BOTANY 

$I.OO 

By    ROBERT    GREENLEAF    LEAVITT,  A.M.,    of 

the  Ames  Botanical  Laboratory.     Prepared  at  the  request 
of  the  Botanical  Department  of  Harvard  University 


Edition  with  Gray's  Field,  Forest,  and  Garden  Flora $1.80 

Edition  with  Gray's  Manual  of  Botany 2.25 


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great  simplicity  and  definiteness  in  presentation. 
^|  The  course  offers  a  series  of  laboratory  exercises  in  the 
morphology  and  physiology  of  phanerogams  ;  directions  for  a 
practical  study  of  typical  cryptogams,  representing  the  chief 
groups  from  the  lowest  to  the  highest ;  and  a  substantial 
body  of  information  Regarding  the  forms,  activities,  and  re- 
lationships of  plants  and  supplementing  the  laboratory  studies. 
*H  The  work  begins  with  the  study  of  phanerogams,  taking 
up  in  the  order  the  seed,  bud,  root,  stem,  leaf,  flower,  and 
fruit,  and  closing  with  a  brief  but  sufficient  treatment  of 
cryptogams.  Each  of  the  main  topics  is  introduced  by  a 
chapter  of  laboratory  work,  followed  by  a  descriptive  chapter. 
Morphology  is  treated  from  the  standpoint  of  physiology  and 
ecology.  A  chapter  on  minute  structure  includes  a  discussion 
of  the  cell,  while  another  chapter  recapitulates  and  simplifies 
the  physiological  points  previously  brought  out. 
^j  The  limitations  of  the  pupil,  and  the  restrictions  of  high 
school  laboratories,  have  been  kept  constantly  in  mind.  ^  The 
treatment  is  elementary,  yet  accurate  ;  and  the  indicated 
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to  be  the  chief  working  instrument,  yet  provision  is^made  for 
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Each  volume  is  designed  for  one  .year's  work.      Each  of  the 
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merly English  Department,  High  School,  La  Salle,  111. 


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^j  In  Part  One  are  given  the  elements  of  description,  narra- 
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writing  and  poetry.  A  more  complete  and  comprehensive 
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grows. 

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TEXT-BOOKS    ON   ALGEBRA 

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ACADEMIC  ALGEBRA 


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